Changing trains in 6 minutes should always be possible. From platform 2 to platform 50 (yellow) you go through the subway (blue). It has stairs (sector B) and a ramp (sector C) down. At platform 1 there is a lift, and also a ramp.
Possibly the second subway in sector D is finished. Then you can also take this path (green).
It is best to get on the train to Martigny in the middle, so that you can get off close to the (blue) subway.
If the train to Martigny is delayed, you can inform the train staff about your travel wishes.
Which train will you take to Martigny?
Kind regards, Reto