Separate appearance from operation
A clean exterior does not prove that a device works. Describe visible marks, missing covers or worn lettering separately from any functional observations. Avoid turning an attractive photograph into a blanket condition claim.
Use specific observations
“The battery cover closes” is more informative than “excellent.” If a function was checked, record the date, the setup and what actually happened. If it was not checked, say so. Keep uncertainty visible in the record.
Keep a change log
When an accessory is found, a part is serviced or new documentation appears, add a dated note. Retain the earlier observation so you can distinguish an improvement from an error in the original description. Let a qualified technician handle questions that require internal inspection.