Device module and electronic device

An electronic device comprising:

• a device module comprising:
• a key input portion comprising a plurality of key contacts;
• a display portion;
• a power supply portion;
• a circuit board that is electrically connected to the key input portion, the display portion and the power supply portion;
• a sheet member, wherein the key input portion, the display portion, the power supply portion, and the circuit board are entirely enveloped by and hermetically sealed with the sheet member;
• a key sheet mounted on the key input portion and comprising a plurality of key tops thereon, wherein each of the key tops is provided to face a corresponding one of the key contacts
• a device casing housing the device module and the key sheet therein and comprising:
• an upper casing having a plurality of openings therethrough, wherein each of the key tops is exposed from a corresponding one of the openings;
• and
• a lower casing that is detachably attached to the upper casing.