There's a new Zest firmware available for download from http://www.my-xda.com/. The filename is Xda_Zest Firmware Update_V7.7.0S.WWE20.00_M4.6.5.P7_V2.1.4 GBR20, which seems to be updates to most of the roms inside the zest. It's installing at the moment, and the upgrade interface on the phone is displaying "GalaxyMini5 Eboot (3.33.0). Since this appears to be a codename for the P565, I guess this is more evidence that the XDA Zest is simply an underclocked P565 and more evidence that P565 firmware may well work on it.