This is a solution from David Sun who successfully repaired the Mercedes-Benz BGA keys. Post here JUST share!!
Some time, you may encounter a Benz, the key remote control function is normal, but can not start the car, or remote control function does not work.
Please open the BGA key (please carefully open), check the BGA chip.
Note 1: repair this pcb key isn’t so much cost-effective
normal soldering iron and hot air sure not enough when you will have 100% re-ball work Big Grin
and orig BGA key shell are not openable, then is needed a new key shell:
There are many MB BAG key available online from China, but most cannot work well with VVDI Mercedes. Some can work with Benz key IR Code Reader, some with CKM100, CKM200, DigiMaster-III. But the key above with a better board can work well with VVDI MB Tool. Users have good reviews of it.
Note 2: VVDI MB BGA Tool for mercedes key programming
BIG THANKS to David Sun from mhhauto forum.