If you just bought a 289 - and it is a new unit - you will have firmware 1.12, which is actually newer than the firmware update available on the Fluke site (1.10 or 1.11, don't remember exactly).
In other words, no need to downgrade your DMM, and since 1.12 was released because of an engineering change (hence the 'not compatible board) and does not contain anything on top of 1.11, you really don't need to do anything!