4 Beeps after turning on

Hi Prius folks! I've been searching here, youtube, and basically google for any info about this. I turn on my (awesomely thanks to all of you, newly furbished Silver Sloop) and in 10 seconds, 4 beeps sound. The only explanation I have found is, 'It's your 12V battery.' Well, I just replaced it. {Is there some reset I need to do, for an electrical glitch to "know" that the 12V is new?}

Secondly, 'your battery in your key fob is bad.' Well, I replaced that, too. I have two fobs, both are beeping.

And, some of you know, I'm heading West from VA in my sloop and, well, 4 beeps is a small price to pay for a running rig. However, I'm still begging from the best of you, "anyone have any ideas? Especially if it's signifying some thing TERRIBLE!" Which of course, I do not want to have happen...Thanks again!

 

well..I did all this AND was dedicated and took 2 videos.

I hope you folks can see them. If not...
In Ready mode, with fob on dash-starts up, engine fires up THEN the CD player lights go on, then roll through a bit through the 6 discs, then at about 25 seconds the 4 beeps happen. It's the same beeps that occur when we go through the MFD when choosing different options, high pitch 'beep'.
In IG ON mode, same thing, just no engine noise. But, same CD show and beeps.

https://youtube.com/shorts/Qz3XFE-XNk8?feature=share

https://youtube.com/shorts/oqfJcE7yQxo?feature=share

 

SFO, no other warning lights, sorry didn't mention that!

 

Hiya,
Well, the first video is in just in the IG-ON mode. There is no initial beeps to turn the car on (two button pushes, NO brake) There are 5 total beeps.

the second one, I am turning on the car with brakes, to Ready mode. There are the 2 quick beeps with turn on, plus 4 beeps.
Kind of confusing! But. Both of the beeps accompany the CD lights flashing...?

 

Nothing in manual, which sucks. : (

 

Wow, AlexY, that's interesting. Second owner, but the guy before was a meticulous retired guy who kept every record and lived the good life in PNW of WA State.

 

Ok, Dolj, this is getting specific! Love it. And/but I can go to my auto place and they can do a diagnostic test? I'll search on this site for LAN and the other acronyms I don't understand. Yet.

Another thing that just happened-I went out for a few minutes. Came in, dropped my -obviously really old fob-and the warning lights and beeps went on in my Prius. Um. Did I push the emergency red button? no. But, it went off anyhoo. So, had to go in car and enter key into car to turn the emergency off. I've never had to go into the car to do that, before. ahhhh. pressure on, when a trip is in sight! Why?

 

Boy, Dolj and bisco have been sharing information on this amazing site for a while! I read posts from both of you regarding reading the System check diagnostic and most of these codes which came up below. So much FUN!!!!! Is the universe telling me NOT to go on a road trip???? Of course, everybody and their brother has a Prius here in Charlottesville. So, ALL the mechanics are busy for weeks....! HELP. hahahha.....