X-ecutor 2.2 Pro bios flashing problem

[gwood]

I'm modding an XBox with a X-ecuter 2.2 Pro using the instructions in "From Start to Finish: A Handguide to Successfully Running a Modded Xbox"
X2BM writes and verifies the chip correctly, but when I reboot the XBox with the enable switch on (blue led comes on) it boots normally (no FRAG) but I l get the splash screen with Microsoft at the bottom, not Executor.
I've flashed X2_4977.bin and X2_4977_02.bin with the same results.
Any suggestions on what to check?