Dell PowerEdge T330 Not Booting - Stops before BIOS at "Initializing Serial ATA Devices"

I'm have an issue with my Dell PowerEdge T330 server, which has suddenly stopped booting properly. Here's the gist of it:

- The server powers on and launches iDRAC successfully, and I can access it over the network.
- However, it fails to proceed to the BIOS setup; it gets stuck after prompting to press function keys for boot options (eg. F2 for BIOS), then the screen goes black. The last message displayed is "Initializing serial ATA devices..."
- The iDRAC system event log is basically empty.
- The iDRAC LCD panel shows no errors.
- The iDRAC power on/off button does nothing.

Here's what I have tried (no changes after any):

- Updating iDRAC to the latest version.
- Updating the BIOS via iDRAC, the update process stalls, indicating it's waiting for a reboot – which suggests the server never reaches the BIOS phase for the update to initiate.
- Reseating the RAM and CPU. 
- Trying different PSUs.
- Removing all storage drives.
- Disconnecting all SATA devices.
- Clearing NVRAM via jumpers.
- Clearing NVRAM vie reseating the CMOS battery.
- Inspected motherboard for any physical damage or signs of failure.
- Looked for documentation on accessing BIOS recovery mode.

Any potential fixes or troubleshooting steps I might have missed?