You cannot keep Shabat if you don’t keep it properly
To keep shabat “properly” you also can say “correct and accurate”
What it means is written fairly clear in the scripture (bible)
The most important is definitely the correct day
But it includes also things like
- rest from work
- do not sell or buy
- do not kindle fire
- and so on and on
Surely there will be no judgement, condemnation or something like that if you don’t keep Shabat complete.
BUT: you will miss lots of blessings if you don’t keep it as much as possible