If you follow the forum, you will find a few post where engine don't run on BCR, but do on batteries.
I have reset one PS-1 with a BCR because it was activated before the BCR could charge. So they are not fail safe for PS-1, you must let it charge.
A partially charged bcr is exactly like a weak battery. Just enough Voltage to allow the processor to try to transfer data, but not enough energy to complete the job. So wait the 45sec to 1 minute. Especially after sitting for a few days/weeks. G