1st gen Zgemma's like star, H1 & H2 the remotes work on any, 2nd gen Zgemma's onwards like H2S through to H7 use the same remote, H9 is different again so only 3 remotes for the whole range of Zgemma's (IF I recall correctly)
With regard to USB & box not flashing, you have two options:
1/ prep the USED USB correctly... Low-Level_format with HDD Guru or similar & then a Full not Quick FAT32 format with Windows before its ready for flash firmware.
2/ Buy a NEW 4gb-8gb Cruzer USB, new/unused drives only need to be FAT32 formatted with Windows to be ready for flash firmware.