I am on Bios 49 for my DZ77GA-70K, and my hard drive and power light are constantly flashing. I also have some issues with my usb/ps2 keyboard not wanting to be detected sometimes. Just wondering if there was going to be an update soon or not.
Go into your bios and reset all settings to defaults. Reboot. Then set the settings like you want. That should fix the power light flashing. (It will flash WHILE it reboots though... but will stop). My USB mouse and PS2 keyboard always work... So maybe switch devices, or possibly motherboard defective? Did this happen before you updated the motherboard? I am on 49 now, and have (surprisingly) no issues.
Also, if this does not work, unplug your PC, take the CMOS battery out and wait about 45 minutes, then plug it back in. The may work also (I don't know why but it will, did for me).
Replace the board. Best way to go honestly. 049 has tons of problem. The board refused to support boot from addon controller card. I can't use 4 x SSD RAID 0 on my LSI card, I must use 2 x SSD on Intel RAID 0. Never had such problem with Asus. Contacted Intel support, all the crap they gave me is the board doesn't support ANY addon RAID controller, and the issue has lowest priority on their list, so in other words, they don't give a crap.