Try to redownload the firmware, maybe just a corrupted file... I don't have any another idea...

Also this firmware is for V1 US version router... Working with CA version too but not with european ones...

How did you update? Via ethernet cable or Wifi? I suggest the cable connection bettween your router and PC... The wifi maybe not stable enough if you PC is too far from your router...

@tony1014 Download for Archer BE550 | TP-Link

I did manually too. Probably is still in testing keenkreations wrote with mine I had to go to the firmware page on TP-Link's website to download it. It wasn't showing in my router firmware update...

Looks like the new 1.09 firmware working fine... So safe to upgrade to it...