I have a somewhat similar issue with a friends bike whereby he was getting the low battery warning for a while. I replaced the battery for him and it worked ok for just a few weeks then low battery warning again, so repeated the process a couple of months later. Again worked ok for some weeks before showing low battery warning. Did it all again a third time with the same outcome. I have concluded that the component that switches power off within the sensor (early type) is not doing so, thereby causing the replacement batteries to become flat in a few weeks. A friendly dealer's parts guy (who owes me a favour) is sending me 2 used sensors from a paying customer's bike who recently had 2 new sensors installed. I'll fit new batteries to them and replace the dead one above and have a spare. I have KDS to do so (delete the old ID and enter the new ID into the bike's ECU). The ID is printed on the sensor and obviously must be recorded before fitting.
Regarding giving the repaired sensor a whirl on the end of a cord after battery replacement, I find this always works ie display shows 0psi plus flat tyre warning. It takes 60-75 seconds for the TPMS to wake up after I start to whirl the thing. I ensure that the sensor is not upside down when doing so.
I hate the thought of 'spinning' the sensor on a string, and the outcome of an "oops" moment, I do recommend the Bicycle tire thing tho, and noted it in the past...
turn your bicycle upside down, and securely duct tape the sensor with some foam rubber padding to hold it in a "as normally installed" emulation on the bicycle rim, between the spokes... then bring the bike right up next to the C14's side, near the ECU, and "pedel that wheel" up to high gear, that should get ya 20mph for sure, and if you bounce the bike a bit, should get that motion sensor sensing....

as for the sensor codes,..
if the sensors had already been registered to the bike, they are stored there already, and the i.d. code can bee seen using the KDS program;
"During sensor replacement, the replacement sensor’s ID must be registered with the Smart
ECU. The registration number can be found on the body of the sensor, or on the packaging.
The exsisting senor's ID numbers can be displayed in Real Time Monitor."
and, the sensor i/d should also be marked on the sensor, at least that's what the book says...
the attached pages also go thru the process for -de-registering a sensor, so maybe that would do the trick, bring the KDS up, and go thru the steps to get to the "realtime monitor", record the numbers for the sensors, both of them, and then de-register (i/d code goes to 0000000) and manually re-register them again 9Input the code number).... this may provide the solution... let us know if it works...
see below: