Acer Iconia A500 problems NEED HELP!!!

Hello, first off I purchased a refurbished acer iconia tab a500 back in 2012. NO WARRANTY

Since then I have rooted it messed around with the ics roms and the common wifi not keeping connected problem happened I tried to do a factory reset and get it to factory, BUT after I did the tablet just restarted and was back the way it was before nothing changed so I deleted a few apps and installed some more thinking it would help and I tried to reboot into recovery mode it just restarted and everything that I downloaded was gone and what I deleted is back. I have tried to reset by going through the settings>backup and restore and the hold power and volume up then flicking the rotation switch back and forth and just get (secure boot: image SOS checksum fail). I have tried reflashing a rom by renaming it Update.zip, and have tried many other things. I do not want to pay $100 to have acer support tell me the things I have already done. Does anyone know how to fix this or what I should do?