KenO wrote:

Checked the forum using keywords "GPX C971" got nothing.

Googled using keywords "GPX C971 schematic" also nothing.

No surprise there.

GPX was probably an importer who bought stuff cranked out of chinese or
korean factories and slapped their name on it.

It was real low end **** that mostly ended up in drug stores, flea markets
and "wholesale distributors to the public".

If there was any service or repair on those, it probably was limited to
bringing it back to where you bought it and crossed fingers they exchanged
it or gave a refund.

You'll have to hunt and peck to make an attempt to repair it, but not sure
what you'll learn from the experience except how low quality can something
be made but if you put it in a fancy enough case, someone will buy it.

-bruce