I just did a clutch change on a mini-me 99 civic.
I got everything put back together and when I turn the key to start the engine I hear a loud click (like a really loud solenoid) and all electrical power is gone. No dash lights or head lights, no power at all. I have to disconnect the battery and reattach it to the terminal to get all power back. Tried it again and it happened all over again. Any thoughts??

Thanks Guys

 

It sounds to me you have a bad ground or battery terminals.. Check and clean grounds and terminals..

 

thermostat housing ground, or transmission case ground