Sonoff mini R2 fw 3.7.6 broken?

[thereal65man]

Ciao! Sorry for my english, I use google translator:
I have a Sonoff mini R2 with firmware 3.7.6, I tried OTA mode without success, I see it in my internet network with IP address, I use rester with windows 10 and I can't get "ota unlock: true"
I tried with the half soldering method (rx tx 3v3v ground) but I can't send the mini into flash mode, using the GPIO0 button I have no blue LED, I tried with the KEY_IN contact which is always GPIO0 and ground contact but nothing , the blue LED doesn't light up and I can't flash the fw.
The button never gives me the blue LED even if I hold it down for many seconds.
From the DIY mode tool console I can see the device, and change the switch OFF ON, but it seems to me that with ON the red LED lights up, while with OFF nothing lights up but you can still hear the relay trip.
So, it seems that something is broken that turns on the blue LED and therefore does not allow me to send it to flash mode. If you have any ideas or advice, thanks in advance. Hello from Venice!

[jrb80]

I found that with firmware v3.7.6 you need to include the deviceid into the json payload. The most complete guide on how to flash Tasmota by @cgomesu does not include this step and therefore I suspect it was recently introduced in a recent firmware update. The official DIY Mode API documentation by @itead does not mention it either.

For example;

{
    "deviceid": "1000c45f33",
	"data": { }
}

I used a Bonjour/ZeroConf/DNS-SD tool to discover the deviceid . Note, some home routers may not support mDNS, I had to install this package in OpenWrt

Here are helpful Postman templates by @lukaskukacka however they will require modification to include the deviceid.