I have a M2s R750ht. I tried turning on ebike after just riding the previous day and the screen would not turn on. I have two batteries. I checked the fuses and charge on both; they were good and full. I disconnected and reconnected all wires. I held down different buttons to reset display. All to no avail. I was about to disconnect and test controller when i decided to contact M2s. Service was prompt and responsive. After a few redundant questions. I was asked about my display. I sent a pic of my 850c display and it was determined that i needed to send it in for an update. This is very inconvenient imagine if I had been on one of my 40+mile rides and the bike bricked. Should be a way to update from home. I sent the screen, they updated and sent it back promptly. It took 3 days to reach me. Other than that, I have had no issues with the bike. Hopefully this helps someone if they wake up to a bike that won't power on. It just may be a display update. Smh.