You have located the led/sw code reader.
That will get you the codes. { see archives]
The trans has a delay shift until temp starts to come up. Normal.
The OVP relay [ aluminum can next to battery] could cause your start problem. They have been up-graded to a new part #.
There is also a fuse on top of this relay that you will want to check.
Next time it does not start, tap relay and re-try....