Problem, has anyone any ideas???

Sequential Manual Transmission: Just wondering if anyone has had this happen.  Went from 3rd to 4th and weird stuff happened. LED display of what gear I was in went blank, light near there (red when in reverse & green in neutral) stared flashing green.
Sequential Manual Transmission warning light came on as did P/S (which means, take it to Toyota asap).
Didn't try to go into 5th, thought I was best to pull over. Changed down in gears fine. Stopped car, took keys out and tried to start it but got nothing, not even the sounds that happen when you do the first turn. (Was as if I had a flat battery feeling) I had to have it towed to my mechanic who didn't get a chance to look at it that day but noted although it felt like the stick was in neutral it had got stuck in a gear. (worked out how to release it). When he went to move it late that day it started fine and he got up to 3rd gear fine just around the car park. He is looking at to what might have caused it doing that. Just thought I would ask the question here.