Does it have a 4500 mAh battery? (= Evergreen)
From the community wiki:
Dogwood weighed 240 g and its 3600 mAh battery weighed 62 g. Chestnut with a smaller 2000 mAh battery weighed 230 g.
The dimensions of Librem 5 (Evergreen) are 153 x 75 x 15.5 mm (6.0 x 3.0 x 0.61 inches). The Power and Volume buttons and the hardware kill switches on the side of the case add an extra 1.5 mm to the width of the phone, so it is 76.6 mm wide. The Evergreen battery measures 60 x 57 x 10.5 mm, which is much thicker than the standard phone battery.
The Birch, Chestnut and Dogwood batches measured 150 x 75 x 15.5 mm, but an extra 3 mm was added to the length in Evergreen to improve the phone’s reception.
And other ways: Frequently Asked Questions · Wiki · Librem5 / Librem 5 Community Wiki · GitLab
After you do a successful flash, you might want to take a look at the Chats app before restoring your backup, just to see if it’s empty this time.