Play store apps downloading forever after factory reset Steps before the problems :

The tablet was inactive, whitout recharging, for arround 1 year and
half.
Acidentaly pressed the keys to 'Download a custom os', and restarted the tablet during the process of download depsite the warning saying i shouldn't.
Did a factory reset trough the config option.

The problems :

All apps from playstore cant be updated or installed. When clicked on install, it will be 'installing' forever.

Cant install apk from outside playstore, i get a messsage  &quot;There is a problem with the analisys of the package&quot; (translated freely from my language). Tried 3 apks so far.

The time is wrong, 1h fowrward, maybe due to summertime.


solutions i tried :

For the problem 1 : Clear the cache and the data of the playstore, the download manager and gmail and forced them to stop (in a lot of diferent orders); Logged out and in the email on playstore (with diferent emails); checked for system updates (had none); checked if internal storage was fine downloading several thing from browser, all downloaded and executed normaly; Tried other apps, working pefectly(one, a store, even updated itself, but i couldnt install its apps as well; Restarted ; did another(s) factory reset; and changed the time manually.
For the problem 2 i just tried to find apk to android 4.0, and im not shure i did it ok.
For the problem 3 i changed the time manually; automatically; selected the region manually and automatcally, rebooted ; and just used the tablet for 2 days to see if would change. Did those repeatedly in various diferent orders.

Nothing worked, for any poblem. The youtube says, when i open it, that i have either the datetime wrong or a bad internet conection, even when i put the right time manually. So i think the time maybe could be causing the playstore problem also ? I dont know. Im tired.
info :

Tablet samsung p5100
Android 4.03
hardware has arround 7 years old
Touchscreen broken once, replaced in the past.
no sd card
The device might be rooted, cant tell, because cant install root checkers (it had the app supersu installed even after the factory reset. I removed it from an option inside the own app and it dosent persists factory resets anymore. Its gone)

Ps: there is no google play services installed, at least not with this name.
Solution to the problem 2 : Just install an valid apk for your current  android versions, in my case, 4.0.3
Solution to the problem 1 : Download and install (using the browser) a new playstore apk for your android version from another trusted store/site, like 'apkmirror'.