Feature phones lack recovery partitions like Android. You must use a PC with Phoenix or a hardware box.
Before diving into the flash file, let’s clarify the hardware. Nokia uses a dual-naming system: nokia rm-265 flash file
When you download a flash file for RM-265, you will see cryptic names. Let's decode one: Feature phones lack recovery partitions like Android
To install these files, you cannot simply copy them to the phone. You need specialized servicing software and hardware (or "cracked" versions of older tools compatible with Windows XP/7): Nokia 6500c RM-265 V10.50 - Frendx.com nokia rm-265 flash file