The seat problem on the Downtown was poor design: two latches with two cables operated off a single source, the ignition switch. Eventually one cable becomes too loose, the other too tight. My simple solution: remove one latch bracket from the seat pan. Two latches is overkill! If your bike has two latches that's my advice: remove one! If your bike has only one latch then you need to adjust the cable length. Try pounding your fist on the rear of the seat to get it to open then you probably have a turnbuckle adjuster somewhere under the seat.
I have the Superdink. It has 2 latches. I had a problem with both latches 1 month ago, not opening the seat. Took it to Mechanic. He stripped the whole body off, loosened the cable and €200 later, it worked. Now I have the same problem but only 1 latch opening. I spoke with the mechanic again who advised me that I needed to change the cable. I do not like the idea of being charged $200 again so, since I am on Lockdown, I decided to deal with it myself. So your recommendation is lock one latch and having the seat operational with one latch only. This is providing I can open it