How to run Apple Hardware Test with broken keyboard?

mid-2011 13" MBA running Yosemite

Coffee spill has left keyboard of mid-2011 13" MBA non-functioning. Even power button doesn't work, I boot by shorting the two solder points on logic board. I've tried to run the AHT with both the broken 'D' and a USB kb 'D'. Neither seems to be registered, as it just boots normally.

Are there any other workarounds for running AHT?

Thanks in advance.