I had a very similar problem that happened with my P-70. I could start it one time and go through a cool down mode and the very next time I tried to start it I would get a power failure. The only way to get it to start again without getting a power failiure was to recharge the battery. The battery would only take around 150mah or so. Initially working with Mr. Matt it was thought to be the ECU battery. Battery was a 6 cell 3100 NIMH and I was able to cycle the battery at around 3000 - 3050 mah. I was pretty sure it was not the battery. Eventually I sent the ECU in and Jetcat replaced the ECU. Problem solved. I realize you are seeing your power failures on power up, but the symptoms are similar.

sean