Project Bike Troubleshooting

   What's up, Reddit? I bought a heavily upgraded Lectric XP 3.0. I'll copy and paste the listing here:

72v 19.2ah 60a BMS battery

Panasonic 21700

4800mah cells

2000w motor from NB Power

45a Sine Wave Sabvoton Controller

 Now the reason he sold it is because he left the key in the ignition in the on position for a week.Now the bike won't power on.  He said the display very  briefly came on once weeks ago.

He suggests it just needs a new controller. I tried a hard reset by completely disconnecting and removing both the battery and controller overnight then reconnecting everything carefully.

Still the bike fails to power on. Any ideas?