I tried to reset the ECU by the battery connection, the roof retracts and closes once, again I have to reset the ECU,
The dealer diagonosed Code B2542, LH Luggage drive motor abnormal pulse, found pulse width for the rear drive motors abnormally low, then high during hardtop operation, The slide control ECU requires replacement for proper convertible top function. The part no (89720-24010)
Please advise... the dealer cost is astronomical.

I see another problem today the fuel gauge is always at low even when the gas is full in the tank, it doesn't move from the low.

 

Sorry to hear about your roof problem. (I have one as well but it hasn't been diagnosed yet.) If you're up for some DIY you can type that part number in an eBay search and you'll find one or two. They're usually about $200-$300. There are also posts on this forum related to disassembling the luggage compartment garnish for access. The ECU is just to the right of the rear fuse block under the carpeted floor of the trunk so you would need to remove that trim for access to it. Good luck.

 

The B2542 error is an abnormal pulse count. But what's causing it? Of course the dealer says its a 1K part and the labor charges. However, we know from the recent rash of roof issues, foreign objects, oxidation, fatigue and misalignments have been the problem. The solutions cost their owners time, but save them litterily thousands of dollars.
The FSM suggest the motor itself, the ECU or the connection harness, and lays out a testing protocol.
Did the dealer tell you the pulse count? Did they offer to do an inspection first rather than just swapping out the ECU? Probably not...
I cannot stress enough how important a thorough inspection and cleaning of connection points can be. It could just be some oxidation the is interfering with the pulse count between the motor and ECU.