Bangle 2. How to set GPS Serial1 baud rate?

The pins I've got from here https://hackaday.io/project/175577-hacka­ble-nrf52840-smart-watch

AT6558 runs in automatic power save mode, I've posted link here http://forum.espruino.com/comments/16320­287/. Although they claim it can be controlled externally.

set it back to 9600 before turning it off.

that may not happen if the application fails for some reason.

As I mentioned, there can be other use cases where the GPS should run "full speed", like 10 fixes/sec, and issuing many NMEA messages per fix (i.e. RMC 10Hz, GSA 1Hz, GSV 0.1Hz). Here I think it would require to increase baud rate.

I think that Serial1 can be switched from one baud rate to another without need to do anything with the GPS port, or turning off the GPS. Like, first step - we issue CAS01 to change BR of the GPS, second step we reset Serial1 to this BR. I remember I did this way with uBlox and other arduino-like boards. But when I tried it with Bangle2, it did not work. What I've done wrong?

Serial1.println('$PCAS01,0*1C');
Serial1.unsetup();
Serial1.setup(4800,{tx:30, rx:31});

May be after that I need to call
Serial1.on('data',gpsdata);
?
then I suspect I will need to replace Bangle.GPSpower with my code completely.