Not applicable

Inspiron 24 3455 Reoccurring Problem after Mainboard Replacement

I'm working on a Inspiron 24 3455. It is 16 months old. It was brought to me by a family member in a condition where it would turn on, but display no video. They said this behavior started after seeing some popups (maybe spyware, I couldn't understand them) and a reboot to install Windows updates.The LCD Built-in Self Test (BIST) worked properly, so I ruled out the display working. From searching around on forums it seemed like an issue with the built in CPU/GPU, so I purchased a replacement mainboard.

I put in a new mainboard today, and reattached the heat sink. I booted up the computer, and problem solved I thought. The computer posts BIOS and can't find hard drive, easy enough fix. I changed the BIOS options to turn UEFI ON, rebooted. Computer booted properly, but into Windows 10 Self Repair, which failed. I restarted the computer, and tried turning Secure Boot on.

I saved and restarted, and now the computer won't display anything. Exact same symptoms as before I swapped out boards. The LCD BIST passes fine, but no display outside of it. The white light on the side button stays illuminated, fans kick on, but never any display. 

Anyone have any ideas? I'm highly skeptical the second mainboard died after less than 3 minutes off on time, but I'm out of ideas.