While I don't have photos of all these fixes, because I was rushing to get them "shipped" before delivering the PC back to my father, here's a list of things I fixed:

• Changed the "no connection" timer in the arduino sketch from a signed integer to an unsigned 32 bit integer. Hopefully that will fix the overflow issue, though the system never went without the app for enough time to confirm.
• As the node app had issues transmitting custom characters, I integrated an up arrow and a down arrow in the arduino sketch, to be used in the upload/download screen.
• On the node side, I made a helper function to better format the strings sent to the LCD. The function replaces the accented letters for their unicode elements (so é would become e´ ), which then I could remove easily. It also filtered any characters not in the valid range to avoid having weird characters in the screen.

With this, the project was finally ready for delivery.