Problems with Reprap XI3

my step dad got a reprab XI3 a few years ago and always had some problems with it so it never got compleated.
one of the problems it the stop switches on the axis. the plate and extruder would not stopp at the motors and would continue before finally stopping. tried to fix by changing switches and swaping wires but it hasent made it any better.
another problem is with the display. i'll push the options button but the menure will flicker for a moment then it will switch back before i can do anything, it takes a while before i can get to the options menue but i'll have limited time before it would switch back to home.
also, when i try to level the plate the screen come up with a cooling down proceidure, but it hasent be used and the displayed temperature will not drop,
Anyone got any other ideas?

Sorry if its long.

One of these ?
[reprap.org]

yeah

Starting with endstops.

Use pronterface move all axis off of the end stops switches and send gcode M119 to read the current endstop status.

It should say
X-MIN OPEN
Y-MIN OPEN
Z-MIN OPEN

with a finger hold down X-min (left) end stop switch and send another M119

It should say
X-MIN TRIGGERED
Y-MIN OPEN
Z-MIN OPEN

with a finger hold down Y-min (back) end stop switch and send another M119

It should say
X-MIN OPEN
Y-MIN TRIGGERED
Z-MIN OPEN

with a finger hold down Z-min (down) end stop switch and send another M119

It should say
X-MIN OPEN
Y-MIN OPEN
Z-MIN TRIGGERED

If it doesn't... that is the first thing to look at fixing.
.

the program keep coming up with a temperature error.
Errorrinter stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
ive tried a few things but still cant get it to work.

ok. having problems with a max temp error. cant do anything till i get this sorted. can anyone help? i have no idea what im doing.

Max temp is often a shorted thermistor

Firstly unplug thermistor plugs from the controller board,. Does the temperature now read a very low or even negative value?

If it does you likely have a thermistor or cabling fault, check the resistance of the thermistor and cable while it is unplugged. It should be about 100k in a 25c room.

If it didn't change reading while unplugged, its a board fault or badly miss-configured firmware