battery or phone motherboard

[mykolaitiss]

hey mine phone do crazy things. when has 2% battery and i do reboot phone booting up i see homescreen back button not work freeze, screen freeze and reboot again i see logo samsung s5, and reboot and black screen, when i put in charger i see 1% or 0%. and when my battery getting low than 1% and shutting down sometimes correct when i see shutting down animation and vibrate when power off, sometimes just goes off no vibration when power off no shutting down animation. or sometimes happens when phones goes to 1% and phone reboot reboot reboot samsung galaxy s5 screen i see and battery dead looks like not have power , sometimes phone battery charged itself when its power off, or 0% left when shutting down. when shutting down with 0% in 7minutes without usage phone the phone battery charged itself 3%. but no see charger screen i dont plug in to the charger . now when power off with 0% i turned on about after 10hour i see 5% and still same issue like 2% when rebooted it goes to samsung s5 screen and turned off when i put the charger i see 2% not 1 or 0% . so why happened in 5% which never happened before just happens when i reboot device on 2%. but now i dont reboot phone in 5% i just turned on after 10 hours ,before phone was 0% completely discharged, so 5% per 7hours charged itself when power off i dont plug charger.