Phantom battery

[john clock colle]

Hi, just changed the auxiliary battery on my 2010 Phantom. Gone to start it, nothing. The dashboard lights light up but no starter motor sounds, nothing. Had both batteries checked by the brake down people all ok, the recovery chap was reluctant to do any further tests as “he had never been called to one of these previously”. One thing I have thought of, an acquaintance of mind that ownes a Phantom said a few years ago that you should never take a battery off without leaving a continuous source of power on the leads. I have changed a few batteries on these in the past without issues, I am now wondering if he was right ? Any help would be welcome, thank you, John.