Send the model and the error
The fastest way to get a useful answer is to include three things: your exact model number, the exact error text on screen, and what you have already tried. "It won't turn on" gives me nothing to work with.
Response time
I reply to most messages within a few days. I am a student, so during exam weeks it takes longer.
What I can and cannot help with
- Can: point you at the likely cause of a flash failure, suggest what to check next, and tell you when a device is probably a hardware fault rather than software
- Cannot: supply firmware files, bypass FRP or account locks on devices you do not own, or take responsibility if a flash goes wrong on your hardware
If your device is not covered here yet and I can reproduce the problem, your message may turn into a full guide — with your permission and no identifying details.