If you reconnected all the connections, then you may have a bad PSU period, it has failed. You didn't give any info as to results other than no display, are you saying, the system seems to want to boot. Are there beeps or some sign of booting life. As for connections they are straight-forward and shouldn't be that confusing. You may have extra connections as to power for other devices, etc.. Just what connect appear to left unhooked or what type are they, can you place some pics of them on a public display, like "bit bucket" or similar picture sharing source? Since, there so many systems out there, even if not HP, that in itself isn't going to hurt to know. HP follows the same convention on PSUs as every other maker out there. You're best bet is to find a PSU replacement and see what details they may provide. On your PSU, find the decal/sticker and note down it numbers, etc. and look for replacement to include a higher wattage one as well, yours is probably at least 200W or better.
Also, you didn't offer why you're doing this in the 1st place, what got you there. If that's possible, post.
I have looked over and over for help with connections from the power supply unit to my HP M7330n and cannot find any specifics. I'm wondering if anyone still owns this PC and would be willing to post here or gmail with me the exact power connections for this PC.
I thought I had everything connected properly but I'm not getting any picture at all.
Any help would be very much appreciated but I'm looking for info pertaining specifically to this PC and not necessarily on PSUs. The HP website is incomplete with their support as has been their chat support.