Mikes100mph

Hey I own a 2017 Yamaha NMax 125cc. This is the first bike Ive owned; I have very basic knowledge surrounding mopeds/scooters. On my way home last night, I stopped for about 30mins to use the bike to charge my phone using the charger port the NMax provides. When I wanted to continue my journey home, the bike would no longer start. When I attempt to start the bike I hear a loud buzzing noise and the engine does make noise as if it’s about to start but does not completely get going. Also, the lights on the dashboard flicker whenever I attempt to start the bike. When the key is in, the indicators and horn works fine. Im assuming it’s the battery which may be low or maybe an issue with the solenoid but I wanted to come to this forum for advice before visiting a mechanic (mechanics/garages for mopeds/scooters around my area of London have a shady reputation so would prefer to DIY). Any response to this thread is greatly appreciated. Thanks in advance! PS. Is it advisable to attempt to charge the NMax’s battery using a car battery? May attempt this when I return from work today.