My 7,1 Mac Pro won’t start. I can’t get past the Apple logo splash screen. How do I get my Mac back? Looks like it can’t find the SSD!?

what I mean to say is, Chime or no chime, if it lights up the screen, your Mac has passed the power-On Self test, which includes a ROM self-check, processor test, RAM test (which in Mac Pro models uses the Error Correction Hardware very aggressively) and is ready to talk to the Boot drive.

If you get the solid Apple, that icon is NOT in the Mac's ROM -- it can ONLY appear after it has been loaded from the Boot drive.

You assessment is not quite right. here is what happens at startup:

The initial "chime" sound is generated in software when your Mac passes the Power-On Self Test. If it occurs and/or startup continues, your Mac is working. The blank gray screen should light up. Then on to the disk Drive.

Accessing the Boot drive:

The solid Apple is not in the Mac's ROM at Cold start. The Apple logo can only appear when it is fetched in the first "blob" of software loaded from a 'magic' place on the boot drive, or re-run after a Restart. Then a whole lot of stuff is initialized, and the progress Bar moves part way across. After a cold start, seeing the solid Apple appear says your drive is not completely dead.

Mounting the Boot drive:

The next step requires a lot of files by name, so the File System is initialized, and the Boot Drive is Mounted. If the drive directory is damaged, the drive can not be Mounted, so your Mac begins one pass of Disk Utility Repair. This will take an additional about five minutes. During this process, the progress bar may be extended, and will grow by an additional amount not seen on a routine startup.

at the end of that process (which should not take more than about five minutes), it will attempt to Mount the drive again:

-- if the drive Mounts, boot-up continues.

-- if the drive cannot be Mounted, your Mac can do nothing more, so it powers off.

-- if the process stalls, this may indicate you have Bad Blocks on your Rotating Magnetic Boot drive (if so equipped). The re-reading of Bad blocks can take a very long time (on the order of a quarter minute for each Bad Block).

Recent Macs do not always produce the chime, but it can be configured/deconfigured with a NVRAM variable.

If boot up continues, your Mac is working fine, and you can make all assumptions about passing previous tests.