Why is PO still in power?
Because they won the election and have a clear majority.
How on earth did they win the elections then?
People voted for them.
1/ It was a fix.
No - Poland isn't Belarus or Myanmar, and if one thing can be said about Poland it is that there is huge media scrutiny of political minutiae.
2/ PO know that they are unable to promote themselves with what they have done, so all they have left is to say 'Yeah this government might be bad but look at what it could be like if you vote for the racist psychopathic conspiracy theorists known as PiS.
It's true that there isn't really any opposition capable of forming a government. PiS couldn't without the helpof an openly racist fringe party and couldn't last a whole term of office.
It is a sad state of affairs when you vote for party not because you think they are the best choice and would do well in charge but because you think they are the best looking piece of trash on the scrap heap.
The same the world over.