Question Computer won't boot after power loss

[FrozenTrout]

So I need some help with a computer that will no longer boot up after a power loss.

Here's the components:

MOTHERBOARD

GIGABYTE GA-Z87X-UD3H LGA 1150 Intel Z87 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard with UEFI BIOS​

PSU

SeaSonic M12II 620 Bronze 620W ATX12V V2.3 / EPS 12V V2.91 SLI Ready 80 PLUS BRONZE Certified Full Modular Active PFC Power Supply​

CPU

Intel Core i5-4670 Haswell Quad-Core 3.4 GHz LGA 1150 84W BX80646I54670 Desktop Processor Intel HD Graphics​

GRAPHICS CARD

EVGA GeForce GTX 970 SC GAMING ACX 2.0​

HDD

Seagate Desktop HDD ST1000DM003 1TB 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive Bare Drive​

SSD

SanDisk Ultra Plus SSD 128 GB SATA 6.0 Gbps 2.5-Inch Solid State Drive SDSSDHP-128G-G25​

RAM

Ballistix Sport 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model BLS2KIT4G3D1609DS1S00​

It was working fine. Then there was a sudden power loss, and now the computer no longer boots up. It starts to turn on for a second and then dies, and repeats that cycle until you stop it. First thought is either the PSU or the motherboard broke.

Here's a video:

http://www.frozentrout.com/Vids/20200418_134528.mp4

There's a two-character debug LED display on the motherboard, but it isn't terribly helpful - one flashes on for a second, but I can't exactly tell what it is supposed to be (like a C with an additional line), and the second stays off, then the computer powers off and restarts the cycle. There's no match in the manual's Debug LED list. There is no beeping.

First, tried disconnecting all USB and other devices, and reseated all the power and data cables, as well as the RAM, which didn't make a difference.

Then, have tried:

• HDD/SSD disconnected (both power and data cables)
• Both, only one, then the other, and then neither, sticks of RAM plugged in
• Video card disconnected
• Only the motherboard connected
• Reseating the CPU fan (even though it already was spinning up)
• Resetting the CMOS

Nothing resulted in any change.

There's an older PSU (Aspire ATX-AS500W) to try, but it only has a 20Pin instead of a 24Pin connector. Tried anyway, and it didn't result in any difference.

I have to admit I've hit a wall here, so does anyone have any ideas or suggestions?

If not, I'm guessing next step is probably getting a new PSU or motherboard, but I'm honestly not sure which is the best to try first (and with current prices, it's not going to be cheap either way), so any thoughts (and suggestions for replacements with a good price) would also be appreciated!

Thanks!

 

[JohnBonhamsGhost]

is it connected to a surge protector? the strip or even a single outlet could have also been damaged.

i would try to find someone with a functioning compatible PSU and try theirs. if still no good; is more than likely the motherboard.

 

[FrozenTrout]

is it connected to a surge protector? the strip or even a single outlet could have also been damaged.

i would try to find someone with a functioning compatible PSU and try theirs. if still no good; is more than likely the motherboard.

I should have mentioned, it IS attached to a surge protector. However, swapping plugs doesn't fix it, neither does plugging directly into the wall.