If you use 5 rechargables, they won't power the screen for very long; once the cells get under about 7.2v the PSone screen doesn't work.
Does that mean I cant use tje 7.2V InfoLithium 4000mAh battery I had in mind?
I have GOOD NEWS though!
It was the backlight that was FUBAR'd
and causing the short. I removed the transformer and the screen is working perfectly now
I had to use a flashlight but everything seems to be OK. The sound works too
And just for reference, I did some testing and found that, without backlight, the screen uses around 180mA without the sound connected to it (might be possible to get it lower if the sound chips are removed). With a sound input connected, the screen peaked at 260mA (I only had 1 speaker connected though so it might be slightly higher with both speakers connected).