Hi 'Kid ... as much as a pain as this seems, you are on your way to learning how to take care of your own computer. This is realtime experience.
There is a pinned post
HERE with some testing suggestions that you might find helpful.
First, remove and reset all peripheral cards including video cards, wireless NIC, etc. Remove and reseat your memory. If you have more than one stick of RAM, try to boot using only one (to reduce variables).
Use the jumper on the mainboard to reset your BIOS settings back to factory default, just in case it got corrupted through handling (see your mainboard manual). You can reset your CMOS back to proper settings later.
Run the (free) test on your memory outlined in the link I provided above. Let it run for 20 minutes, should be enough.
If no joy, do a repair reinstall of XP (no need to totally reformat again, just choose the second screen offering to repair XP; do not choose the Repair Consol).
Try these to get started and post back how its going.