Information related to the DFU. If you are here, you have activated the mechanism temporarily removing the DFU protection from Upsilon.
Since Espilon update 16 (updates from the official website numworks), your calculator is locked and you will end up with a multitude of inconveniences. Thus, to avoid any unintentional update, we have implemented this mechanism to block unrecognized updates. However, if you know what you are doing and you are sure of what you are doing, you can press button 6 3 times in the menu or go in the usb settings and then plug in the calculator which will then be unprotected.
NumWorks article : https://www.numworks.com/fr/blog/logiciel-securise/
More complete article : https://tiplanet.org/forum/viewtopic.php?f=97&t=24968&p=261770#EOTB1