Esp32 and api specialist needed for pos device upgrade

We need a deticated esp32 firmware specialist to take over on a critical project. As it is now, we got a payment system where our clients are able to pay for services via a QR code on different devices. All works well, but we need a flow change so that instead of polling the payment provider, we need to poll own servers instead, and the payment provider will then send a notification to our servers when a client checks in. Most of it, is already made, but current developer is suddenly unresponsive, so need someone to finish the work ASAP. The hardware works by getting power from the machine in question, and then pulses on the coin acceptors pulse wire, there by adding credit to the device. Please look at the following documentation from the Payment provider here BEFORE you bid on the project.. [login to view URL] [login to view URL] A big issue is that we got a lot of live units by clients already, so the update must be done over OTA, some basic things are hardcoded, like pulse pin, and if its state high or low etc. and we need that to get to the server somehow. We will start the project by you looking at the files and giving an estimate of the hours needed, then after we do a test period. Keep in mind this is just one part of this project, you will get quite a bit of related work with upgrades on the same project after.