You have to replace nr. 1. <control type="button">
1. should be <control type="button" id="15">
Summary(my way):
#ssh to the box
ssh root@<ip-address>
vi /storage/.kodi/addons/skin.confluence/720p/DialogButtonMenu.xml
# use cursor down key to go to an entry like <control type="button" id="nn">
# entry ends with </control>
# use cursor down to go one position under </control>
press i key
copy/paste
<control type="button" id="15">
<description>Reboot to Internal</description>
<width>340</width>
<height>40</height>
<textcolor>grey2</textcolor>
<focusedcolor>white</focusedcolor>
<align>center</align>
<textwidth>290</textwidth>
<texturefocus border="25,5,25,5">ShutdownButtonFocus.png</texturefocus>
<texturenofocus border="25,5,25,5">ShutdownButtonNoFocus.png</texturenofocus>
<onclick>System.ExecWait("/usr/sbin/rebootfromnand")</onclick>
<pulseonselect>no</pulseonselect>
<font>font13</font>
<label>Reboot to Internal</label>
</control>
Display More
press esc key then :wq (save and exit)
Change skin described by the_bo in 6.
6. Switch to a different skin and switch back to confluence to refresh skin (or you can reboot box). Press letter s on your keyboard to bring up the power menu.
You can select "Reboot to Internal" in shutdown menue using confluence skin