First check your card. Do a full overwrite and formatting with the "SDformatter" freeware and if it looks good run the "h2testw" freeware on it, again doing a full overwrite. This may take some time with larger cards and older computers. The end result should show the card having nearly it's full rated capacity with no errors. Put it in the cam and format it there, then test for proper cam functioning.
If the cam is still bootlooping with that (or another known good) card, then it may be a powering issue. I think this cam uses a miniUSB port for powering (most cams do) which is the same as an android phone wall charger. Try powering the cam with the wall charger, and if it works the cam PS has probably gone bad.
One more possibility is that the LiPo battery in the cam has failed. Sometimes using the phone charger will overcome this while the car PS, which is less powerful, can't. The easiest diagnosis for this is that the last vids taken when the cam is shut down will be corrupt and unviewable because there was no power to close those files correctly. So if the wall charger trick works, run the cam for a bit then unplug it. Pull the card and check the last file to see if it's corrupted. If it is corrupted then the cam's LiPo battery is bad. If that file plays normally then try the car PS similarly. If it still bootloops or the last file is corrupt then the car PS is bad.
If after all this it still bootloops with wall charger and in the car, then the last thing to try is to reload the firmware on a freshly-formatted card, place card in cam, then power it up. It will either load to FW and begin working properly or the cam is dead and you'll need a replacement.
This cam uses a LiPo battery, not supercaps, to close the last file correctly. LiPo batteries comnmonly fail in hotter climates, but they can also fail in cold as this type of battery is not meant to be charged below freezing temps. Dashcams don't have a temp sensor to prevent that and begin charging as soon as the cam turns on, so if it's been charging below freezing much that might have killed it's battery. It's a real shame they didn't do what most cam manufacturers have done and began using supercaps instead as this is a pretty darn good cam otherwise.
Not sure what the warranty situation is as this cam was recently discontinued because HiSilicon raised the chip prices drastically making continued production unprofitable, so unless they held onto some for warranty replacements I don't know what the outcome will be. Again a shame for a cam this good.
Phil
