Maps 2016.20 crashes Nuvi 1490

I can't install 2016.20 onto my Nuvi 56 for a few days, I will report back when I have checked it out. In the mean time, I would try a proper power down of the unit (rather than placing it in standby), with the unit on, press and hold the power switch until 'Turn Off the Device Cancel / Off' is displayed,( this can take between 3 and 10 seconds), select Off, the unit will then do a full power down. When turning the unit back on from this state it may require a longer than normal press of the power button

If the above doesn't help the restarting, you can try a master reset, but BEWARE, this will set the unit back to factory defaults and delete your Favourites so make sure they are backed up somewhere.

1) Place the unit in full power off as shown above
2) From off touch + hold lower right hand corner of screen
3) Briefly press power button until logo is displayed
4) Continue to hold lower right hand corner for 30 seconds
5) When Garmin logo disappears release lower right 'touch'
6) Logo re-appears, with copyright information
7) Re-apply touch to lower right hand corner
8) "erase all user data No / Yes" message is displayed
9) Select Yes

 

I have now installed 2016.20 on a Nuvi 56 and run it for over 2 hours without a restart, one thing I noticed is that when 2015.30 was replace with 2016.10 is that the unit was left with only 2016.10, however this time the unit has retained 2016.10 and has added 2016.20 as another map. If you have both maps on your Nuvi, I would suggest you select only the new one (see picture below) as it may be that having both maps selected could cause a problem, then try the 'Full Power Down' followed by the 'Master Reset' detailed above

 

It may vary from model to model, but on the Nuvi 56 it is >> 'Settings' >> 'Map and Vehicle' >> 'My Maps' to get the screen in #3

I looks like your Nuvi powers off and resets the same, but doesn't give you an on-screen message, here is a scection from page 4 of your user manual :-

 

I think it is unlikely that you downloaded a 'fixed' version of 2016.20 this time, it's more likely that the first download was corrupted in some way, It is a bit strange that Garmin Express would even try to re-download something that it thought it had already downloaded though. Ah well, at least it's fixed now