Hello.

I have a Olivetti Echos Pro150 SL, which isn't working.
Like I said in the title, it first turns on, then starts beeping and after that, proceeds to shut down. While this happens, the screen stays black.
It does 1 beep with a pause followed by 3 more beeps. Unless it turns itself off, it repeats this beep code a second time and stays silent afterwards.
Sometimes it just turns on and shuts down, without beeping at all.
I already did some researches on my own. One person said, this beep code means there's something wrong with the CMOS Ram and another person said it'a graphics chip / vram related issue. Both things are possible.
I noticed, there are several things wrong with the machine. First, this Laptop has been taken apart before, and second the CMOS battery had leaked.
I immediately removed the CMOS battery and cleaned the whole motherboard by using 99.9% isopropyl alcohol, diluted vinegar and dried it carefully.
I havn't viewed the board under a magnifying glass yet, but it's very likely, that there's some damage, caused by the battery acid.
Is it possible that a CMOS battery is required for this thing to boot?

Has someone an idea, if this is fixable and if yes, how?
I appreciate any help. Thanks in advance.

Here is a recording of the beep tones: https://youtu.be/qL5VoX1ncMI
Sorry, the video is turned 90°. That wasn't supposed to happen. I recorded it on my phone.
I'll also make sure to add pictures ASAP. Until then, I beg for a little patience.

edit: after doing some further researches, a third person pointed out, that the RAM could also be the problem.