Yes, it was a bare metal sheet before applying the sticker the first time... when I didn't know what would happen ;-) I ordered a new one but the sticker was already there and the bare metal part was not available anymore. The only part I could order was just the stickers.

The sticker doesn't look removed yet. You can try to heat the remaining part and remove it with a spatula, being careful. Good luck Not really fan of this material, much prefer PEI sheet but this printer doesn't offer this choice and you can't get just bare metal plate.

That's finally what I did and worked fine since : took Octoprint and forgot the touch screen. Never had that problem anymore.

Indeed, that's what I discovered the hard way like you. Thanks for the advice, I'll try to find BuildTak of 200x300mm. I changed the plate for a new sticker and it was really a nightmare to remove and clean. I had to use a all lot of acetone and its just a mess to remove the sticker glue.

This seems to be a bug in the screen firmware. After the screen crash and reboot, re-printing will give a perfect print, with no freeze. It's a shame because the first crash takes more than 6 hours to happen.

Not sure the sticker is made for PETG printing. Lowering the heated temperature to 65°C and upping the Z of 0.1 helped not destroying the sticker and allows removing the PETG part. But this leaves a trace on the sticker : like a bubble that has the shape of the first layer. So in the end not suitable for direct print. I tried even lower bead temperature but the piece didn't stick and came out after few printed layers. Si I guess you lust use a separation layer between the sticker and the printed object so it doesn't harm the sticker : but not very nice cleaning it after. Not tried yet as removing the glue on the sticker isn't something I am looking for.

Finally got it right. After checking everything, I came to change the spring coupling part. As I have the dual extruder, it makes a lot of weight on them so on one side it was totally compressed when the head was on that side. My guess is that when moving the Z axis, the compression of the coupler would change the Z height. As seen on YouTube, I put a 1/4" roller ball between the stepper motor and the lead screw so that they are in contact and the spring coupler can still do its job compensating, but not Z axis. Now the first layer is correct on all surface ;-) Hope this can help others in may situation

Well, not what I expected. It seems the Y is now flat but can't change it further as any lowering of the front Z motor will lower the rear. Also for me I can't change from the bed as the enhanced aluminium heated bed doesn't have any spring (as the initial bed), it is directly screwed on the structure. Did I miss something here ? So I am still left with a subtle Y height difference from front to rear : better than before but still miss a layer or so from end to end. The rear part (from the screen) has no first layer.

Many thanks for your advice. Didn't know the y axis must be flat as I thought the auto level would take care of it. I'll check all what you said and will tell you how it came. For now for sure the y axis isn't flat.

Sorry you couldn't make it with this one. It sure is complexe to build and calibrate but I still think this can be a very good printer. I succeeded in solving nearly all issues with single hotend, only stuck with this trouble. Just hope there are still people behind it so I can get help.