I'm trying to keep this short and save you time.
It's 100%ly sure that I burned my Uno by doing mistake with breadboard (20 volts ment for stepper motor driver went in from the 5V regulator pin) Please, dont ask how/why..:
- Windows found new harware during the "burn".
- all outputs connected to stepper motor drivers were protected by 220 ohm resistors.
- all 3 stepper (Allegro A4988) motor drivers died.
- Uno do not reply to anything and Windows do not detect it.
- Led comes on, and I'm able to measure 4.8V from the 5V reg. pin.
- no smoke...
So, my question is it worth to trying to repair Uno by changing components, what? The chip with the bootlader costs something 7 euros and it's pretty easy to change, but what do yoy say?
This is not catastrophe, 4 new Unos already ordered, but if this is controller easy to repair, who not to try?