I converted a Ford Ranger to electric 12 years ago using a ElCon PFC 3000... I have had no issues until now. The charger will not activate in spite of the pack low charge state.
I don't think that Elcons have been around for 12 years, but if the Elcon is old (say over 5 years), then the usual mechanism of the MOSFET protection capacitor going high internal resistance with age may have kicked in. The capacitor that they use is longer life than the cheapest option (it is rated for 105°C), but in my opinion it should really be a longer life part. Of course, that would add a dollar or two to the cost of manufacture.
Do the LEDs still come on? There is the red/green LED, but sometimes you can also (or instead) see the red LED from inside shining through the yellow sticker. Though I'm unsure how that works with a 3 kW charger, which has two 1500 W chargers in one box.
It is possible that the charger is OK, but the BMS isn't telling the charger to come on for whatever reason. In this case, there IS a way to temporarily force the charger to come on. You need to short pins 1 and 3 of the 7-pin connector. Unscrew the plug, and use a good flashlight and/or a head magnifier (etc) to see the tiny markings on the front of the connector. You need to short pins 1 and 3 with a short piece of wire. The pigtails of a 5 W resistor are about the right diameter. If the resistor is of low value (say less than 100 Ω), then you don't need to cut the leads off the resistor, use both ends.
WARNING! All these pins are connected via low impedance to the negative end of the pack, so isolate the pack from the charger somehow before doing this, and be cautious. Using an insulated-handle pair of needle nosed pliers would be a good idea. If possible, use the blue cap to cover the 7-pin connector with wire inside to make the whole thing safer.
If you want to have some assurance that you have the right pins before shorting anything, you should see 11-13 VDC from pins 2 to 3 (3 being positive), when the charger is switched on (not necessarily charging). Shorting these pins together is not good, and will likely burn up an SMD fuse inside the charger (not terribly convenient to get to), which your BMS likely needs to see. So be cautious with this test too.
[ Edit: had the 12 V pins totally wrong (sigh!). The charger is enabled by pulling enable (pin 1) high, not low. Needing to connect pins 1 and 3 is still correct, fortunately. ]