I have just moved into a new apartment and the showers in both bathrooms have not worked properly since I moved in.
1. In the primary bathroom the cold water comes out in a trickle for both the tub faucet and the shower head. Maintenance has been over and even replaced the "seat" but did not make any difference to the cold water performance.
2. In the Master bath the hot and cold water worked perfectly fine. The tub faucet and worked very well and the shower head was like water dripping from wet noodles! Not much pressure at all.
Now the shower in the master bath will not come on at all, or if it does it shuts off within about 3-5 seconds. It doesn't matter if the hot water is running, the cold or both.
What can possibly be the problem?

1. In the primary bathroom the cold water comes out in a trickle for both the tub faucet and the shower head. Maintenance has been over and even replaced the "seat" but did not make any difference to the cold water performance
Did they flush out the cold water supply? Replacing the seat will not help a pressure problem.

2. In the Master bath the hot and cold water worked perfectly fine. The tub faucet and worked very well and the shower head was like water dripping from wet noodles! Not much pressure at all.
Remove the shower head and find a small rubber washer with holes around the outside. This is the water saver. Pry it out and toss it. Shower better now? Good luck, Tom

Did you try the shower with the shower head removed?