Battery issue?

What is the issue? It sounds like they're using one of the new electronic testers. I'm familiar with the older style that loads the battery to simulate running the starter motor.

What kind of problem are you having?

Sorry. I just saw your other post about the fuel issue. Since you have a fuel pressure gauge, run the hose under the back of the hood and clip the gauge under the wiper arm so you can see what happens to fuel pressure when the problem occurs. Also, tell me if that pressure drops to 0 PSI soon after you stop the engine, or if that pressure holds for a long time, as in many hours.

Sounds like you have the GTS model. If I remember correctly, they used a relay box similar to those used on Daytonas. I'll have to research this, but for now, look under the dash, near or above the steering column, for a black box with about a dozen relays. I seem to recall those relays were not removable and if there was a problem, the entire box had to be replaced. Today I would pursue taking one apart to look for broken solder connections, but I wouldn't want to experiment with a customer's car. That brought back memories when you mentioned the hidden headlights. Two relays in that box were for that system.