Do you install a beep on MB? If yes, I guess no beeps mean MB issue.
alxnilsen, your power supply is marginal at best, but I think you should be able to boot. The ASRock MB does not have a speaker, please buy one (buck or two) and then you can post the beep code. creatie said as much. Maybe more coffee/meditation. Try one memory stick in various slots, if you have not. Good luck and enjoy, John.
Your motherboard has the correct minimum BIOS for your Ryzen 2400g which is P4.60.
According to ASRock Support, your Memory IS NOT LISTED on its QVL list for the Raven Ridge APU: ASRock > AB350 Pro4
DDR4 HyperX 2666 2666 8GB HX426C16FB2K4/32 Micron A-die SS 2/4 DDR4 HyperX 2666 2666 8GB HX426C13PB3K4/32 Hynix A-die SS 2 DDR4 HyperX 2666 2666 8GB HX426C13PB3K4/32 Hynix M the SS 2 DDR4 HyperX 2666 2666 16GB HX426C13PB3K4/64 Hynix A-die DS 2
According to your link your Kingston RAM MEMORY Number is "HX426C15FBK2/8" This may be the reason you are having problems. The RAM MEMORY installed may not be compatible with the Ryzen APU.
You also have a new BIOS Update for your Motherboard: ASRock > AB350 Pro4
4.90 2018/7/12 7.28MB Instant Flash 1.Update PinnaclePI-AM4_126.96.36.199 Patch A
2.Improve PCIe detection with Raven Ridge CPU
3.Keep the XMP setting after system restoring from G3 state.
* If the current BIOS version is older than P3.40, please update BIOS to P3.40(Bridge BIOS) before updating this version.