Need some help diagnosing issue

Hi, I have a Creality Ender 3 Pro and have been printing for a few years. I will preface this by saying I am a moderately mechanical female with little to no skills when it comes to the software side of things. I have put together all of my printers, replaced parts and diagnosed and repaired some issues, but please be gentle with me!

About a year ago, I was having some issues with my machine. I can only vaguely remember what was going on, but it wouldn't power on. I swapped out the cord with another machine, no luck. Then I swapped the power supply, no luck. I was frustrated and let it sit until recently. I replaced the board with a silent board, and replaced the hot end.

The machine turns on, but emits a long beep, stops for a second or 2, then cycles through this. The screen displays the regular start screen but is unresponsive. I tried flashing the software for the new silent board. When I flashed the firmware, the screen blinks to solid blue, but then goes back to the elongated beep cycle. I have checked all connections, twice.

Does anyone have any suggestions?