Just 3 high beeps after Factory Reset

[Toxster]

Terra Master F5-221 6GB RAM
TOS 5.1.33
4 x 4TB Seagate Iron Wolf
1 x 500GB SanDisk Ultra 3D SSD
Files Backuped on a 12TB Seagate USB Disc

I recently updated from 4.2.40 to 5.1.33. After that I reinstalled some apps from the TerraMaster Community Place and had issues with restoring my MariaDB for Nextcloud. Issues were that for example documents saved in /Volume1/htdocs2/ folder were erased with every reboot and also some settings like configs were reseted after reboot. So I thought there was maybe an issue with my RAID-5 or the HyperCache (because I also was not able to remove the HyperCache) of the F5-221. That's why I deleted the volume and than the raid while still inside the F5-221. After that I created a new TRAID storage pool, then I did a factory reset and got stuck with a NAS not going to initialize. I tried several things like removing the drives and so on, but nothing helped (always heared a low beep after power on and some seconds later 3 high beeps, trying to access the NAS led to "ERR_CONNECTION_REFUSED" and ssh login was only possible with root/admin to a rescue system). Then I found the guide to burn a new usb boot device, so I installed Ubuntu 22.04 on VMWare and burnt an USB Flash Drive. Opened the F5-221 and exchanged the USB Flash Drive. I then tried to start the NAS with drives attached and without, but it didn't start (same topic of 1 low, seconds later 3 high beeps). Then at some point suddenly I managed to get it to initalize, but only without the SSD pluged in. So I directly installed TOS 5.1.33 onto it. Then after the installation finished I inserted the SSD and activated HyperCache. After that I did the installation of apache24, PHP8.1_okm and MariaDB with phpMyAdmin and started to look whether my problem is still there. And yes, still had the issues, that after reboot the htdocs2 folder was empty. Also deleting the HyperCache didn't change anything. Also I was having some other issues like problems with sudo and so on, so I thought I should go back to 4.2.40 to get at least my Nextcloud back running and find out about background of the issues and upgrade to TOS 5, when I know how to solve it - so I started a factory reset. After 5 Minutes I got a screen with "Loading please wait..." and after 20 minutes I opened another tab in my browser accessing my NAS - got "ERR_CONNECTION_REFUSED" and restarted. Since that time I hear 1 low beep and seconds later 3 high beeps, when powering up the F5-221, no matter whether the drives are installed or not. In the meantime I got a SATA USB Device to connect all my drives to my windows PC and erase the partition from the discs, so they are factory fresh - result still the same. So, can anybody help me to get the F5-221 back to initalize? (and also some information about the beep code would be nice)

[Toxster]

Some impressions of what I get, when trying to access my F5-221 without drives in it.

[Toxster]

Ok, I reburned the USB Flash Drive and also changed the Battery at that time. I connected a Display to the HDMI Port. Here is a screenshot

[Toxster]

Ok, using Firefox instead of Chrome i was able to connect to my NAS and initialize TOS 5.0 and get my system back running after inserting the 4 HDDs.

[TMroy]

You do not need to burn a new USB drive. when you hear 3 beeps after reboot, this means your USB boot is working properly, but it just fails to find the OS from your hard drives.