ESP8266 Community Forum

Hello.
I have ESP-01S and it was working well. But memory size was not enough for my task. I bought W25Q32FV and replaced original 1 MB chip. After replacing I turned it on and noticed that blue LED is flashing in quite weird way, like there is bad connection. I turned it off, cleaned up remains of fluxe, turned on again - now blue LED is always on in programming mode. In normal mode it just blinks once at boot-up time and then it is off.
I can not upload any firmware on ESP-01S, because serial connection can not be established. I could not solve it and decided to install original flash chip. Result is the same: blue LED is always on in programming mode.
I was soldering in careful way, I checked that there are no short-circuits, that chip is installed according to it's key. I'm using USB programmer to flash ESP. So, I tried using different USB ports - result the same. I installed ESP into another 4-pin adapter (like this - https://www.aliexpress.com/item/4001054 ... 4c4dVbhj7c) - result the same.
Looks like ESP is damaged, but why in this case it can successfully blink 1 time by LED in normal boot mode?
Yes, I can buy new ESP but before that I would like to know is there any way to fix this ESP? Any ideas? May be I didn't consider some details? I would really appreciate any help.

I am afraid you did break something there. And ESP8266 can always be contacted with the serial flashing tool, e.g. for reading the MAC address, it will work even if no flash is connected at all. If you can't successfully read the MAC address, something is really broken. The ESP8266 does not need a (working) flash for the running boot loader (which is in ROM).

Hm. Probably you are right. Thank you.
I tried to turn-on ESP with flash chip removed - behavior is the same.
Interesting, what can went wrong during chip replacement? Procedure is extremely simple. I would like to repeat it with new ESP, that I will buy. So I would really like to know what was wrong, to avoid killing new ESP
Btw, I remember that from the very beggining this ESP was behaving little bit weird. Ex, when it is ON, LED is off, but if you touch connector by finger, LED sometimes can become ON. Finger is dry, it could not act as conductor. May be all ESPs behave in the same way, but for me it looks weird.

Then I think the PCB indeed already had a small defect. I don't think careful soldering is able to break stuff easily. Only thing I can think of is excessive heat, which will kill both the flash memory and PCB traces, it may even break the ESP8266. I assume you have some experience in soldering SMD though.