The screen on my phone went completely black and will no longer turn on from what iv tried i cant hear or seen anything and there is no sighn of water damage what do i do?

I will try and keep this short. I have a Motorola Razr (puchased in the USA..... this will make sense later) and I lend it to my brother when he visits me from Canada. (Roaming charges for Canadians using their phone in the US is insane) He too has a Motarola phone that he brought with him. The Charger that he brought with him was for a Canadian phone. Apparently, you cannot use a charge for a Canadian phone, on a USA contracted phone..... I'm not sure why, but it is the case. He attempted to charge my USA phone with his Canadian Charger and the screen went blank. The phone was still on and could even receive calls. Even when the calls came in, the screen still remained blank. I won't bore you with any more details.
Here is how I fixed it:
- Unplug phone from Canadian Charger
- Take the battery out of the phone.
- Plug in USA built charger (without the battery in the phone)
- The phone attempt to charge
- Screen should turn on. Wait till screen indicates (Cannot charge battery)
- Plug battery in.
- Hold down power button to turn on the phone.
- Phone should be in working order.

I don't claim to be an expert. This may only apply to my particular situation. Hope it helps if you happen to use the incorrect charger. Take care.