Ok, so how would those checks and balances work if the president refuses to obey the courts? Who's going to enforce those court orders? I suppose you could say that the congress could impeach - but what if the majority of the House sides with the president? And if the House does manage to pass impeachment, it still takes 2/3 of Senators to convict - as we've seen that's a very high bar and very unlikely to happen. But let's continue the thought experiment and say that the Senate votes to convict - who's going to enforce the conviction and kick the President out of office?

The employees of the executive branch are not intended to be a check on the executive branch's powers. They are the agents of the executive.

The legislative and judicial branches are the checks to executive power.