I have sold about 500 Hi8s last year, and there are only two units with power problem, so i dont think there are problems with the circuit design.
The working Hi10s also come with the 1538 chips, i dont have a defective Hi10 unit to compare.
Anyway i use a programmer to read the bios from a working Hi8 pro and flash it back to the 1536 chip but nothing happenned, open the shield and lost warranty with that one but no luck, im ordering the 1538 one to replace it, i will update the process soon enough.
Here is the Hi8 Bios .bin file for anyone who need it.