Your problems are two-fold. Firstly, you appear to be using POA when there is no reason at all to do so. The whole point of POA is to allow the driver to be “at work” (and so being paid) while not actually working, thus allowing his paid time to exceed the WTD limit of 60 hours.
Secondly, you appear to be allowing the tachograph machine to dictate your working/driving time. The tachograph is not infallible.
You are correct that the 2hrs 35 min of POA has “reset your driving time” - this is simply a result of the programming of the tacho unit to count all POA as “break” (when in fact it should only be counted as Break when the card is in Slot 2 under “multi-manning”).
Simplest solution is not to use POA (do you actually need to use it?). Slightly more complex solution is to work out for yourself exactly how much driving and Break time you have accrued and ignore the stupid machine and the warnings/messages it flashes at you.