Car won't start and will not turn over

[S62]

Well I just installed new rear calipers on my car and when the car was on jack stands I left the key in the ignition and it died. Once I was done doing the calipers + bleeding the brakes I tried jumping the car.
Nothing happened though, no clicking, nothing at all. I tried different jumper cables and a different car but it didn't solve anything.
I'm seriously pissed right now. My cars been on jackstands since monday and I thought I would have it running by tonight. I've already replaced the battery. This means I have to get driven to school again by someone else.
The car is an 87 325is. I about to go and buy a tin to calm myself..

[TurboJake]

Or use that money to buy a battery.

If everything else checks out, of course.

[S62]

Car starts again, I waited and then tried jumping it again. Weird

[BrownBeanE30]

well alteast its fixed

[S62]

well alteast its fixed

Ya, for the time being till something else breaks lol

[a3ternus]

Ya, for the time being till something else breaks lol

Thats the golden rule of driving/fixing an E30! ;)
N.