Huawei Ascend G730-U10 won't torn on and Vibrating, How to Fix it?

Hello everyone.

i've 2, G730-U10, and i've got these problems.

First :

Phone won't turn on, when i'm plugged in my charger , sometimes red light will turn on for seconds, sometimes won't, and sometimes just for a second. in other hand, i connect my device to computer, and nothing happend but my pc recognized a USB Serial Device (COM4). i tried to turn them on without battery and with usb cable, bcs i don't know batteries are really working or not, i mean they're working but some people think, it could be battery problem. i don't know, i just tried to turn them on without battery. so these are the problem for first device.

Second device :

this phone won't turn on, red light will shown for second and sometimes blinking for seconds, and when i try to turn it on, it's gonna vibrate repeatedly. and i've also tried to turn on without battery. and about recognizing in pc, my pc just recognize some unknown names.

So these are all the things i knew and i can tell, please if it's possible, help me to understand what's going on with these both device.

Thanks and sorry for bad english.

Best Regards,

Eskandari.