If something were cooked, it wouldn't be intermittent. I'd aim to the driversdoor and or the wiring inside the boot to the door. Here's why.. is there always someone with you when it happens? Likely not.. so it's very likely the door.

This reminds me of when I was trying to diagnose a bad brake hose in a car. I asked my buddy to explain to me how to diag it. He simply said "I could..but it'll take longer than you swapping a new $12 line on and being done, trust me".

Give it a try..