Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, for the "...Does the unit have a replaceable battery? Where is it/ ..."; please click HERE.
Please be forewarned that battery removal may and can cause lost of memory.
All others would be internal and would require that the unit be opened up for visual inspection, voltage/continuity/resistance checks, confirm faults and effect repairs.