Bootloop and battery won't charge

so i was flashing existenz MM and i can't go to recovery mode, before installing it i have xzdual recovery installed, so i thought i can just flash it again (and ofc it was stupid because after that i just know xzdual won't work with MM) so it's bootloop even when i charge it, the problem is the battery died and it won't fill the battery, the phone keep restarting when plugged in with charger so it keeps draining the battery before it filled up, i can't flash it because of that, the question is, how can i fill the battery so that i can flash it using flashtool?
thanks, and sorry if my English is bad.