PS3 YLOD After Cleaning and Reapplying Thermal Paste

I have a Cechb01 I bought from eBay and it worked fine when I plugged it in at first. It was very dusty and the fans were kicking up a bit high but otherwise it played the games fine. I decided to disassemble it and clean it out and reapply the thermal paste. I put it all back together and got the YLOD. I don’t think I missed anything but has anyone else had an issue like this?