Will failed start with almost dead battery throw P0380 on 96 W210 diesel?

Basically, my battery was shot. I tried to charge it up and start, but basically I got one or two chugs.
I probably turned the key a bunch without waiting for glow plug light.

Now check engine is on with P0380 code.

Will disconnecting the battery clear this?

It would help to post the code description.

Yup, it certainly can. That is a glow plug circuit error. It is also possible you toasted the relay.

Pull the battery, clean the terminals extremely well, we're talking shiny contact surfaces and slow charge the battery to full voltage or replace.

You'll probably have to clear the code manually.

https://www.obd-codes.com/p0380

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

OK. Will do.
Also, the glow plug light only goes on for a few seconds before going out.

Is this relay located on the passenger side by the firewall?
I didn't even know that was a fuse box. dang!

Any link to test that relay?

Front of driver fender well under hood.

__________________
Jim

Do the battery service before you start chasing relay problems. Low voltage can cause a shortened or erratic glow cycle.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

I just traded my totally blown, sulfated, open celled, overheated and swelled 3 year old interstate battery for a decent used battery with no labels, (but it's the right size and shape) from the interstate dealer. He just did an even swap.
I will clean up the battery posts and leads. Then put some dialectic grease on it.

Is there anything I need to check on the battery that I can do with a tester?

If you had a 3 year old battery swell, check charging system voltage, it might be too high.

It was not the system.

It died because it sat for 1.5 years dead.
It took a charge and held for a month.... but then my kids left the dome light on and it sat dead for two days and that was the end of it.

I charged it and it only achieved 10 volts... dead cell.
I opened it and two of the cells were low so I filled with distilled water.
When I charge it it smelled like sulfur.
It swelled on the charger overnight.
It was very hot.
I took it off the charger.
It remained hot for at least 10 hours. Even though it was in the shade.

Check for voltage. If it is lower than 12.3, put it on a trickle charger or battery maintainer until it reads 12.8 or so. Just as a "I know it's right" thing.

Generally when you get a new battery from a store they are usually only around 80% charged.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

I just checked it.

After I left the trunk lid open for the past 30 minutes and it is at 11.83.

Putting it on an old school charger at 2 amps overnight.

That ought to do it.

Update.

I just installed a brand new AGM battery and I get no check engine light and no "check engine electronics" warning.

Congrats!

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now