Like all modern electronic items such as satellite receivers, routers, phones et.c, these cameras have on-board processors, which store a basic programme set plus all additional menu commands made by the user.
Sometimes all these instructions get scrambled and the equipment starts to behave erratically or not at all.
If your camera develops a problem which doesn’t have an obvious answer, then the best course of action is to force a system reset. You can do this by removing the SD Card and all the Battery Cells; and then leaving the camera for at least 24 hours, which will allow all volatile memory to discharge.
Afterwards, you start to set the camera up again as from new providing this appears to have cured the problem.

Before you contact your supplier read all below.

Dirty switch contacts. If your camera refuses to switch on (either switch position) or when in the test position, comes on then dies and then comes back on again. Remove all the batteries and try spraying a small amount of switch cleaner into the body of the OFF/ON/TEST switch and then gently work the switch back and forth through its positions. Using switch cleaner will clean and lubricate the switch contacts which can become dirty over time.

Dirty card contacts. SD and SIM card contacts, on the cards and inside the camera can get dirty over time. If the camera suddenly starts to behave unusually when it’s worked OK previously, try cleaning the card contacts by lightly spraying the card contact face with CD or screen cleaner and then gently working the card in and out of its slot a few times. This will clean the contact areas between card and camera.

6210MC SD card lost inside camera. The reason the card is able to go in at an angle is because the non wireless MC only has a plastic blanking tray where the module would normally be fitted. This leaves a small gap at the back of the card slot. If the card is accidentally pushed through this gap it lands in the blanking tray, which in itself should not cause any problems. To remove the card open the back battery cover and you will see the front of the blanking tray, directly below the card slot. To the middle left of the blank is the SIM card slot and to the right of this and above is a lip which can be levered with your finger nail to pull the blanking tray out of the camera. Do it carefully and the SD card should come out with it. Keep the camera normally orientated while you do this and gravity will keep the card at the bottom of the tray. Once you’ve removed the card you can either choose to leave the tray out or refit it.

Camera shows the Acorn Splash Screen and then dies when switched to test. No SD Card or SD Card faulty. Insert SD Card or try another card. Clean contacts.

6210MG refuses to switch on in test position with SIM card inserted. Try cleaning the SIM card contacts. This may work!

Camera does not accept menu changes. This can be caused by low battery voltage. Replace batteries.

Camera set to Camera + Video but only shoots images. This can also be caused by low battery voltage. Replace batteries.

5210 Microcontroller (MCU) problem. Some recent cameras have occasionally shown a fault where, although the menu sets up OK and all functions work in TEST mode, when set to ON the camera will take one image and then fail to respond to the PIR trigger. If you are unfortunate enough to receive a camera with this problem, you will need to return it, through your supplier for replacement/repair.

Faulty SD Cards. SD Cards can also go faulty causing the problem mentioned earlier in this post. If you suspect this, then try a new card. Some cards can be incompatible with the camera so you may need to try a different brand. This may be indicated by getting a Card Full message on the screen. SanDisk are compatible.

Card Protected Message on Screen. Make sure your SD Card Lock is off.

Important: Do not format your SD card in Windows. Format in the camera.

Setting a Password. This can be a problem if you forget what it is, or if when entered, the camera doesn’t respond. If the above system reset doesn’t cure it you will need to return to your supplier or manafacturer to have it reset.

Screen message saying ‘Please reupgrade’ and camera does not work. This indicates that the camera has been loaded with the wrong firmware update for that model. You will need to load a new firmware update using the correct file for the camera model.

Firmware Updates and Acorn lookalikes sold by Aldi and Ebay. I don’t know the origins of the cameras sold by Aldi but firmware updates for the Aldi cameras and Ebay counterfeits are not compatible with the genuine Acorn cameras. If you try to update an Acorn 5210 with Aldi or counterfeit Ebay firmware you will stop your camera from working. At the current moment I don’t know if the resulting condition is recoverable.

Flickering White Screen and buzzing noise from camera. Batteries need replacing and you may see a blue screen with low battery message.

Black Night Time images and/or Shortened Videos. The cause will most likely be low batteries. As the battery voltage decreases with use it will eventually reach various thresholds.
1) Length of video will be progressively reduced to 0 seconds.
2) IR light will decrease on still images and the images will become very grainy.
3) Camera will still take images at night but they will be black other than to show external light sources.
4) Day time images will still be taken but no videos or one/two second clips.
5) Camera stops functioning.

Batteries and Video Length. If the camera is taking videos which are a variable and shorter time than you have set, it will be because the battery voltage has dropped and the camera is attempting to save battery power.If the camera is operating in low temperature, use Lithium batteries or an external Sealed Lead Acid battery rated at 6 volts 7 Ah. The SLA battery will last for a long time.

At temperatures around or below 0C. Alkaline and NiMh re-chargeable batteries will only work for a few days before their voltage drops to too low a level. If you have to use these battery types then reduce the length of the video to 10 seconds, or just shoot still images only.