P400 Chipless Problem - stuck firmware upload process

[Justin Walker 0]

While performing the first few steps to convert an Epson P400 to the chipless firmware (the first upload test, to determine if the printer will work) it keeps getting stuck at 55%.  What could be causing the test to hang at this point, consistently?

[wic.support 30]

Did you try to upload firmware in normal mode or program update mode? What message is shown on the screen before you start update and in what color? Also, what version of the firmware did you use?

[Justin Walker 0]

Follow up to this issue: after multiple attempts, it became clear that timing the initial process is crucial. 
Once we timed it right and got the flashing lights, we were able to upload the firmware successfully. 
Thanks for the reply!