Asrock Taichi X399 stuck in BIOS update

motherboard suddenly stop working , but power supply was fine , ram , water cooler , gpu ,was running then all chassis fan , CPU fan stop working , no display, i removed cmos battery and put it back and everything is start running but no display and gpu fan was running at 100 % speed then i tried to update BIOS and i followed the exact process which mentioned in manual ( flash bios ) via usb but green light keep blinking fast then slow in loop i kept that for 2 hours but still its only blinking ,now it almost dead no sign of anything just green light blinking , i need your help regarding repair or troubleshooting the motherboard.