TomTom XL IQ routes - soldered in SD card not recognized

[Rataplan]

Hi,
I've got a TomTom XL IQ routes (V3?) which has only 2GB of internal mem. So I've soldered in a 8GB MicroSD card (no SD--> MicroSD converter because of lack of space) and the device does not recognise it. What happens is when I boot the device connected to my pc, I get into file-transfer mode and that works fine, but I only see the internal flash mem. When I boot without USB, it starts booting, the yellow bar runs, then TomTom logo again, but then it stalls. When I disconnect the SD-card it works fine with the internal memory. So far it seems I haven't fried anything But also it seems with the card connected, it DOES make a difference as it won't do a regular boot with it anymore.
I've used this schema:



I've quadruple checked the solder points, and tested with my multimeter to other via's of the solderpoints, to make sure it's correctly wired up, and as far as the picture above goes, it is. I must say though that picture shows WR6_V1.3 on the board, while mine says WR6_V1.4. The layout is the exact same though.

I also have a smaller TomTom One IQ V5, which is pretty much the same board (but a bit different layout) and I've modded that with the exact same type / brand of SD card, and that works fine.

The XL had bootloader 5.5282 if I remember correctly, but as per [Only registered and activated users can see links. ] I downgraded to 5.5138. First I tried 5.5128 (which is running fine on my One IQ v5) didn't even want to install, I guess some sort of idiot-proof before flashing. Downgrade to 5.5.138 worked fine but the issue is the same.

By the way, this is a 8GB SDHC card, I tried with a 2GB SD card (so non-SDHC) but that resulted in the same issue. Now I've read on a polish forum [Only registered and activated users can see links. ] I might need to actually remove the internal memory chip, but I've never had to do that on any other TomTom I added SD cards to.

Anyone can help me?