The following post talks about entering the processor bootloader. Entering the bootloader could have unintended consequences should the wrong commands be entered. Proceed at your own risk.
Note, this is for a series 3 JNIOR that went out of production in 2015. You can upgrade to Series 4 JNIORs easily in most cases.
Most JNIOR3 batteries should be dead and therefore removing power to reboot should restore the default accounts. If the battery is still doing its job you can force your way in using the following:
If shorting the jumper pins or inserting the jumper briefly does not reboot the JNIOR and accept your ENTER keystrokes, then DTR is not wired or asserted.
This test was done using Putty on an Ubuntu system with an old USB-to_Serial adapter.
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