TC won't boot after drive replacement

I have a 1TB Time Capsule model A1254. Not sure exactly how old it is, but likely 3+ years if not more. A year or so ago, the hard drive started to die -- I could hear clicking and noises from within the unit and the TC functionality itself became spotty.

Recently, I decided to dig the TC up and see if I could replace the hard drive to bring it back to life. I followed the excellent manual located here on iFixIt and replaced the drive with a 1.5TB Seagate model.

After replacing the drive and powering the TC, the front light lights green for a few seconds, the fan started to go, and then everything shuts down. It does this every time I try to plug it in. If I replace the old hard drive back in the TC, it boots up with an amber light (which is what it did before.)

Thinking that it might be the power draw from the new hard drive, I checked the power consumption specs. The old drive consumes .680A @ 5V and .850A @ 12V. The new drive consumes .720A @ 5V and .520A @ 12V. Power consumption shouldn't be the issue - the new drive consumes less @ 12V and only .04A more @ 5V.

Just for grins, I also tried a 2.5" laptop drive and it produced the same result - green light for a moment, then powered off. It can't be drawing more than the original 3.5" desktop drive.

Any other thoughts here on what this could be? Possible, I guess, that the power supply is simply dying as has been mentioned so often previously, but the unit powers up with an amber light with the old drive, so I don't think that's it.

Is there anything special I have to do to the new drive in order to get it to be recognized? I formatted it MacOS Journaled but that didn't produce any special results.

Thanks in advance.