Should I pay full or part
Low refrigerant can cause freezeups which can result in water leaks, but it's difficult to say definitively who is at fault in cases like this. Overflowing drains are not unusual, but any system installed overhead should be equipped with (a) a primary drain, (b) a secondary drain and (c) a shutoff switch in the secondary to turn off the AC system if water builds up in the secondary drain (and possible a drain switch in the primary drain line, for even more protection).
Without knowing what the electrical problem was, it's hard to say whether the first tech could have even checked the system out thoroughly. If the system were tripping breakers, for example, then the tech may not have been able to run the system long enough to check for proper refrigerant levels. However, AFTER the electricans finished up, the techs could certainly have done so (and should have).
Leaks happen, but as long as there are sufficient safeguards in place you can generally catch them before they cause troubles. .