WEMOS Mega Board

Hi,
I've this board:

And my application is finished and running fine besides one issue: It do not run from a cold boot, I've to press the reset button.
I've an serial device attached to the Mega2560, communicating to the ESP8266 (this is a bit crappy). From cold start, the L LED on the board is on, if this LED is on I cannot program and my application is not running because the Mega2560 is somehow dead. When I press the reset, LED L is blinking second and then going off. After that I can programm and my application is running.
Do anyone knows what the LED L is for? It is connected to the Mega2560...
Ist there any setup to use a serial port from ESP8266 on this board, I do not need the Mega2560 anymore, this could also solve my issue.
Where is connector J9?

It would be great if someone has answers because currently I'm stuck with this board.
Best Mario

Start by posting a schematic as you have it wired, not a frizzy picture.

Begin met het plaatsen van een schema zoals je het hebt bedraad, geen kroezige foto.

Thanks for letting us know how you got it working.
Vielen Dank, dass Sie uns mitteilen, wie Sie es zum Laufen gebracht haben.

I've got it: This board has some issue during cold boot with communication between 2560 and 8266, not sure why but there is no possibility to solve this. I've used now J9 which is connected to the ESP for communicaton. That solves my problem.

Anyway, this board and the environment is a bit crappy...thx.