To install the bootloader, you cannot use a simple USB cable. You need an or a second working Arduino. Method: Using an Arduino Uno as an ISP How to Flash/Re-flash a Bootloader on an Arduino Nano
Since 2018, Arduino has used a "New" bootloader based on Optiboot. Most clones still ship with the "Old" version. (ATmegaBOOT) New Bootloader (Optiboot) Upload Speed 57,600 baud 115,200 baud (2x faster) Watchdog Bug Causes an endless reset loop Fixed (standard behavior) Storage Size Takes up 2 KB of flash Takes up 0.5 KB of flash IDE Setting ATmega328P (Old Bootloader) ATmega328P [Source: Arduino StackExchange , Thing-King ] How to Burn (Install) the Bootloader arduino nano v3 0 bootloader download
Look in .../Arduino/hardware/arduino/avr/bootloaders/optiboot/ . To install the bootloader, you cannot use a simple USB cable
You can find the latest source code and pre-compiled .hex files on the Official Optiboot GitHub . Most clones still ship with the "Old" version
Updating or downloading the bootloader for an is a common task, especially if you have a clone board that refuses to upload sketches or if you want to benefit from the performance of the modern Optiboot standard. Where to "Download" the Bootloader