booting issues after bios flash

[bmx6454]

hello, I'm having some issues posting after flashing my bios from the original 1.20 to the most current 2.70 on an asrock z270 extreme4. The reason i decided to flash it is i read that the later revisions had improved memory oc stability, which i am in need of. After it finished the flash, It restarted as it should, and then it just sat there turning on and off over and over again without posting. no image on screen either, no beeps. it will eventually boot up if i restart it a few times, and it will remain perfectly stable once its on. i have had other mobo's do the same thing, but not from flashing, from failure. i find it more likely that something either went wrong with the flash, or my mobo doesn't like this revision. i would re-flash it to a previous version, but i was hoping for a second opinion before i do, as I'm a bit gun shy now lol. thanks in advance.

 

edit: forgot to mention that it also will not turn on at all if i keep the usb stick i flashed it with in the pc. maybe that's normal on this mobo?

 

asrock z270 extreme 4

6600k

h60 cooler

corsair vengeance lpx 3000 16gb (8x2)

asus rog strix gtx1070

samsung evo 970 plus 500gb m.2

kingston 256gb ssd

1tb 7200rpm hdd

evga 500w 80 bronze

[bmx6454]

bump: haven't shut it down in 3 days now out of worry that i wont get it on again. any advice?