Hello!
I hope this finds you well!

I recently was given a GP3 but I am having some issues...

when i turn it on the display goes to straight blocks(*attached picture)
I tried to Hard Reset but found the standby button to be ?not working?
-it comes on green when powered up but doesn't go RED when I press it to attempt to go into standby.

The daughterboards have been reseated & I have also attempted to start up the unit both with the battery pak removed & the daughterboards as well.

I am not sure what operating system is installed.
(*also with that, I will need a W98 operating system to upgrade -correct?)

Any advice/assistance is graciously welcomed!

-All the best!

Try swapping the boards around in their sockets. This probably won't help but it's worth a try. If you give me your email address I'll send you the needed files and instructions on performing an update to the Promega 3. Some of these files are too large for normal email, but if you have Gmail, the zipped files will be sent via Google Drive so should work. I have successfully used a Windows 10 PC to update with. Just make sure you have the appropriate cable as described in the document I send.