Electron using 3rd party SIM blinking green

One of my Electrons was working fine with 3rd party SIM and few days ago started blinking green … I’ve tried everything - updating code with STARTUP(cellular_credentials_set(“internet.tele2.ru”, “”, “”, NULL)); string… flashing again … adding setcreds etc… no reaction - still blinking green…
assume something wrong with Electron itself …
any way out ??
maybe Hard reset of Electron ?? but how to hard reset it ??

The usual way to get close to factory default woub go via DFU Mode

particle update
particle flash --usb tinker
# or for third party sim, upload the binary you got via setup.particle.io
particle flash --usb <customFirmware.bin>

thanks for helping out…
when I turn Electron to DFU mode Windors device manager asks for Proton DFU mode drivers - existing set of drivers doesnt fit (((
what should i feed there ?

You need to install the DFU drivers via zadig

Here is a tutorial

@ScruffR thanks a lot for guiding in this hard situation
finally did all you’ve said

C:_particcle\tele2>particle flash --usb firmware.bin
running dfu-util -l
Found DFU device 2b04:d00a
checking file firmware.bin
spawning dfu-util -d 2b04:d00a -a 0 -i 0 -s 0x08080000:leave -D firmware.b
dfu-util 0.8

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2014 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to dfu-util@lists.gnumonks.org

Opening DFU capable USB device…
ID 2b04:d00a
Run-time device DFU version 011a
Claiming USB DFU Interface…
Setting Alternate Setting #0
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 4096
DfuSe interface name: "Internal Flash "
Downloading to address = 0x08080000, size = 5948
Download [=========================] 100% 0 bytes
Download done.
File downloaded successfully
Invalid DFU suffix signature
A valid DFU suffix will be required in a future dfu-util release!!!

Flash success!

at the end is says “Invalid DFU suffix signature” but Flash is success! -
but still bninking green…

That suffix message is no issue - that’s normal.

Is the antenna attached properly?
Have you got the LiPo connected and fully charged?
What version CLI have you got?
Did you do

particle update