Unplug both connectors to the hdd, and see if it will successfully boot that way. If it does boot, go into Diagnostics and format the hdd. If not, you must replace in order UI PWB and Main Board.
Hello I followed steps ,unplugged two connectors on HD. It only booted up to upgrade screen. Replaced UI pwb first then Main Pwb and it only boots up to upgrade screen and stops there. Is there anything else to try or is this a replacement at this point
Ok. Until replacement you can format your HDD attached trough a USB caddy (rack) to a computer/laptop, or to replae the HDD (of course FAT32 formated). After that try to reinstall the software.
Other thing is to make a short to MAIN Board battery.