Hey everyone, I weren't here for a long time

In this time I replaced my XV signature for a
Roomba 980 which so far has been doing great.
While cleaning my storage room I remembered that I have the neato laying around in there- with its batteries connected.
Tried to boot it up - and it worked! let it charge and it EVEN CLEANED- but happiness ended early when after about 20 minutes of cleaning the robot threw me a "Battery level is low" issue.
I thought that maybe it's calibration issue so I have let it charge while I slept. Tried to fire it up again, and before 5 minutes passed it said that it has a LIDAR error (3000).
Now I remebered why I have even replaced it in the first time: My lidar was causing problems, replaced the motor and it worked again. Then it would clean for very shorts periods of time, so I replaced the battery and it threw LIDAR problems again.
Anyway, I didn't give up and because I read somewhere that maybe the LIDAR fails because the batteries (which might make sense becaue they haven't work well from the start) are bad.
Before spending even more money on a dodgy robot, I calibrated it via "recharge" tab through neatocontrol.
I let the fan work at full speed, and monitored how long it blew. 55Mins before it turend off. Is it normal or should I invesigate money on a battery pack?
I really want to make the robot working again becuase it may be nice to have a 2nd robot to clean regularly on the 2nd floor, but I don't wanna risk spending too much on that

And how about you? Is the 55mins fan runtime is OK or not? if not, it may be the cause for the failure of the LIDAR?
Too many questions and the internet doesn't seem to make me less confused
Anyway, any help will be appreaciated, and I thank all of you in advance!