Scooter won't start - this issue became progressively worse over time

[peonpete]

Hello, as the title says my TaoTao 50cc Atm 50a1 is not turning over anymore. The electronics seem to be working fine - the lights come on, the horn works etc.

The issue is when i try to get the bike running it just makes a slow noise as the engine cranks, it sounds like it is trying to start but it can't.

I have swapped out the starter motor with another start motor and it still has the same issue. I also swapped out the starter relay and that didn't fix it either. I fully charged the battery and it *did* turn over once, however when i tried it later it did not...So i fully charged the battery again and this time it didn't start the bike.

So at this point i am thinking [though unlikely] that it is a battery issue and i am going to test that soon.

If anyone has a idea of what the problem could be please let me know since i won't to get this scooter running reliably...

Here is a video of the sound i get when trying to start up the bike [using the electric start]: