The phenomenal is gradually worsening, from at the beginning it fails to boot occupationally, to a prolonged period that it refuses to boot continuously but once booted, it is all right for the whole day even between power cycling, until today it enters a wdt reset loop for an hour, then completely refuses to boot.
All I have now it boot message as
ets Jan 8 2013,rst cause:1, boot mode:(3,7)
load 0x40100000, len 29288, room 16
load 0x3ffe8000, len 1972, room 0
load 0x3ffe87c0, len 7364, room 4
The module draws 200mA at this stage.
I wonder if anyone has observed the same phenomenon. I have ruled out firmware issue since I have tried many versions of firmware all have the same result. I guess the flash chip died (but it writes successfully). Maybe I'll popup the metal can and replace the chip to verify.