Please try to update the attached BIOS file for TEST only with the following procedure:
1. Unzip attached TM740_A2O.zip into bootable FDD.
2. Use sum.exe (command line= "sum 740_a2o.bin") to make sure bios checksum is "2CE0900" 
3. update A2O BIOS (command line= Aflash /f 740_a2o.bin)