x370 killer SLI/ac & Ryzen 5 3600 won't post

Hello all! I'm having trouble getting my new PC to post at all. The board will power on, fans kick on, and red LED is pulsing, but after about 30-45 seconds, then entire machine turns off, then restarts. It won't post anything at all. I bought this board as a combo from Newegg with a Ryzen 5 3600. It seems that these boards might require a BIOS update to run the 3200 speed RAM I bought, so we tried with some 2399 a friend had but it still would not work. I've tried booting with and w/o hard drives, and with w/o an m.2 SSD, and cleared cmos. The first board/cpu i received from Newegg did the same thing, and now this replacement second board is repeating the exact same behaviors. I'm looking for anything that might help me out. Newegg did comment that the first board would not post for them either, but I'd like to think that the chances of me getting two boards that are dead on arrival would be very slim to none. They've also stated that they've not had a high number of returns/issue with this combo and that it should be compatible, and basically told me to screw myself. I'll list full specs below, any and all help would be very much appreciated. TIA!

MB: x370 Killer SLI/ac
CPU: Ryzen 5 3600
GPU: Gigabyte GeForce GTX 2060
RAM: G. Skill Ripjaws V DDR4 3200 (2 x 8GB)
M.2: WD 120GB SSD
HDD; Seagate 2tb, and 500 GB

The bios "sticker" says P3.20, but it's sharpied out. Newegg claims that this board is Ryzen 3rd gen ready, but it seems like the BIOS is the obvious issue, but their customer service is a joke. It also seems that it doesn't natively support 3200 speed ram, but we tried to boot with 2933 a friend had handy and that didn't help at all.

p.s. bios version 3.20
means the board left asrock in 9th or 10th month of 2017..............

where has it been for 2 1/2years...........

and the sharpie may indicate 'someone' has updated it's bios but to what version ?
it needs version 5.40 or above released 8th july 2019

thers 8 different bios versions between your sticker/factory bios and the required one

As I've done more research I'm beginning to believe that it is new old stock as you suggested. I tried clearing the cmos as described in the manual, but I'll go ahead and give it a go the way you suggested and see what happens. I'm pretty sure that it won't have onboard graphics, but I've already removed the GPU so I'll see what happens when I attempt and let you know! Thanks a ton for the advice!

i didnt say use on board graphics

i said just have cpu 1 stick of ram AND GPU