Well. No idea exactly what I fixed it, but it now works.
The ROM I used was Acer-A501-Build-021.
First I loaded a ROM (which I can't post a link to as I don't have 10 posts) by renaming it update.zip and putting on the SD Card and doing the vol- power thing
Then I used Skrilax_CZ's bootloader V8 to get the ROM I wanted on there. I left it with Android on the screen for a LOOOOOONG time and it eventually booted. I had previously left it for a couple of hours and gave up.
Anyway it works. Hope this helps some else. This was a serious pain in the arse! Well done Acer.