If anyone is interested, the battery for a 70mai A800 or 70mai Pro and possibly the A800s, can be purchased from here -- https://vi.aliexpress.com/item/4000942106956.html?spm=a2g14.120574184.108.40.206bf1ec90hOp40
Does anyone know how to replace the battery ? Anyone have a video of doing it ? It seems my local dash cam supplier left out a lot when he said "remove two screws under the paper sticker and pull apart". The video for the 70mai Pro does not work.