On first update from W8.1m to W10m all keyboards except english must be removed, and this instruction is generaly missing. All builds 10586. xxx do not work at all on LUMIA 640 XL DS, or it works a few days and than phone starts to heat, restart and generaly be unusable. I'm afraid, Microsoft has forgothen a difference in SOC between LUMIA 640 LTE and 640 XL DS non LTE. First is Snapdragon 400 version 8926, and second is version 8226. So i'm afraid that even final build won't work good on 640 XL DS. Can anyone help and fix this. 640 was announced as first future w10m phone, but after expensive 950 rollout, seems MS has forgothen on it.