Help with fastboot, please

Hello everyone. I'm new here and I'm looking for someone who can help me with step by step to uhh... fix my phone. It's a Lenovo s650 and I have tried to flash it via fastboot, but to no avail. And because of that, I'm here now. Please take a note that I'm not that good with these things so please bear with me. Anyhow, the phone is now kinda retarded. You know those pop ups, saying that something has stopped working, yeah... basically, I'm getting spammed by em'. So, there's no time really for me to do anything on the phone like going to the settings or even changing the usb mode to debugging without being bombarded by em' every sec. Thus, the reason why I want to flash it. (cause I think flashing is like turning them back to beginning, like after a reset?) Oh, and before that I have already tried hard reset. That, of course, didn't work. :crying:

Please help :)
P.S. Sorry if something is wrong with my English. But I hope it's adequate enough for you guys to understand what I'm trying to say.

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