I had a similar problem setting-up my Bluetti EB240 the problem was the supplied 7909 to MC4 adapter. The polarity was reversed so the male MC4 connector (which is embossed '+') was in actual fact negative. Thankfully no damage seems to have been done to my MPPT by fitting them the wrong way round. There was no error message on the display (just blank) which is how I ended-up searching for answers on this forum! The outer part on the 7909 should be negative the inner part is positive (check this before connecting panels to power-station if you are worried about doing damage). First time poster Hello BTW ?
