moved into new larger enclosure. dragon is stressed

yesterday, i got a brand new 120 gallon terrarium after hes been in a 40 gallon terrarium. the old terrarium had a mat for the flooring (not the green fuzzy mat, it was a smooth, peach colored mat) and with the new cage, we put in substrate (dirt and play sand mixed together). we dont have much in the enclosure right now so its kinda empty. my dragon keeps going to the cooling side and staying there. i held him and he was very cold so i put him by the basking side. he stays there for a couple minutes then goes straight back to the cooling side. he also has visible stress marks. how can i calm my beardie down?