(it wasn't an adapter, but a direct line. used adapter to make it easily understandable)

First of all, I've read a similar topic in this forum.

Q: Does Mi (4C) Routers have any Fuse/reverse-supply-protection?

Because I didn't found anything like that on the circuit borad. A mechanic in my home town, also said IT IS DEAD!

Now is it somehow repairable? that... he doesn't know?

I've read in that thread that, replacing/removing the fuse would be the solution! But is my router even have a Fuse, I don't know! If anybody knows, please let me know.

Or, Is there any other to fix this? Also please let me know.

Thank You.

 

Do you mean it was AC instead of DC?
Open it up and see if anything obvious at first.
Or what items/devices are directly connected to the input.

 

Welcome to AAC!

What voltage was supposed to be applied and what did you apply?

Did you see smoke or smell anything burning?

Have you opened the unit to look for damage?

 

If the router is more than 4yrs. old it is unlikely to be repairable, even if you could source replacement parts which might be a dubious proposition if any proprietary parts were damaged. Have a look, just in case you get lucky.

 

I've accidentaly plugged AC Power Adapter to my (Mi 4C) Router, and now it isn't working at all. Is It Repairable?

No

 

A mechanic in my home town, also said IT IS DEAD!

 

You may as well take the time to open it up to take a look. It's either that or the dump.

I couldn't find anything online about whether there's an internal fuse. Even a fuse may not have protected it from irreversible damage - they don't blow instantly and damage can be very fast.

Maybe you'll get lucky and see something to attempt a repair.

 

If I understand you correctly, you were supposed to supply low voltage - maybe 5 or 12 volts DC. But you hooked it to line voltage of 120 or 240 VAC. If that's the case you now are the proud owner of a paper weight. Or it could be one of the first exhibits in your new "Museum of Abused Electronic Parts".

Is it reparable? The general consensus is "No". Not unless you have thousands of dollars of equipment and access to the necessary parts. It may be reparable IF - and that's a BIG IF - IF you got lucky and blew out only a fuse. Chances of that are about the same as hitting the lottery and having the only winning ticket for $1.5 billion.

Sorry for the bad news. Easiest route is to get a new router.

 

A clear photo of the circuit board where the power entry happens would be helpful. Without more information I would say you've Westinghoused your router.