Top control modules really don't go bad. I cant remember, since showing up here in 2009, where a TCU fixed anything. You might read my "Top Sensors" thread in the Roadster forum if you haven't.

Now, you say "Trunk latch" will work, but what I think you mean is that the electric lock will operate, is that right?
Keep in mind, the TCU will only activate that lock IF, and only IF, it has all of what it looks for from the sensors and modules.

... The CLP/SSM has to agree.
... The divider/top open sensors must apply a ground to the pin at the TCU. (Not checked when putting top UP but is checked when putting top DOWN.)
... The BCM must respond to the TCU's interrogation with "go ahead" - which means the windows are either down or going down, the car is not going over 9mph, the BAS/ESP system is working right and the wing is either fully UP or fully DOWN.
... The trunk latch switch indicates that the trunk is fully closed.

If there are issue with the power windows, BAS/ESP, CLP/SSM or if you have a top cylinder indicating a 'bad' or 'wrong' position, OR if the TCU has simply lost track of the top's status, the top won't move and the lock won't engage.