ESP8266 Community Forum

ESP -07, previously responding to AT commands. I tried to upgrade firmware and failed.
Now I get only constantly flickering blue LED and cannot send AT commands.
This message received on terminal is constantly repeated at 76800 baud,8,n,1:

ets Jan 8 2013,rst cause:4, boot mode:(3,7)
wdt reset
load 0x40100000, len 25052, room 16
tail 12
chksum 0x0b
ho 0 tail 12 room 4
load 0x3ffe8000, len 3312, room 12
tail 4
chksum 0x53
load 0x3ffe8cf0, len 6576, room 4
tail 12

chksum 0x0d
csum 0x0d
Fatal exception (0):
epc1=0x402411b4, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000

Any help appreciated
Thanks

I've trouble-shot many ESP boot problems with this reference
https://github.com/esp8266/esp8266-wiki/wiki/Boot-Process

Note that MTDO is gpio 15.
I think your issue is gpio15 is high instead of low which it needs to be.

Please see my post 'NOT SOLVED ESP-07 endless loop-jmp user1, Fatal excption(0) '
Your problem seems to be like mine.