I agree with the above. It sounds like you have a short somewhere. Unless your battery was on it's last legs I'd bet it's a short. Was everything OK before the solder job? If so then start there. You may have a piece of solder that is causing a short. This is especially likely since the signal unit is not working as well. Charge up the old battery and check you light cluster again. With luck that will take care of everything.

__________________
LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold