I recently up graded my 600 G1 HP pc with a new a case I also upgraded my psu from 240w to a 500w and added a rx 550 graphics card to the mother board when I finished building it i did put the original hard drive in it when I started it up it came with a hard drive error so i told my self okay I have more hard drives I plugged a differnt one and started to computer but this time it would not even power up its like its getting no power to mother board or anything can someone help me pls. also could it have to do with when I tested it with NO thermal paste/glue
Without seeing the PC, it's hard to say exactly what may be wrong, it's possible a power connector is not plugged in properly so you can start by checking all of those.
You can also run through the troubleshooting guide located here to see if that makes any change: https://community.microcenter.com/discussion/2818/tech-article-how-to-troubleshoot-a-newly-built-pc-that-will-not-post-boot-power-on
Submit photos and a description of your PC to our build showcase
See other custom PC builds and get some ideas for what can be done
Services starting at $149.99